I have an older zyxel router I wanted to use as an ap to extend my network in my garage. I decided to load openwrt on it since it's eol with the vendor so I figured why not. I set it up and got it working on my network as an ap and my main router being the dhcp server.
The problem is the zyxel in the garage running openwrt is now crashing daily, sometimes within 5 minutes of rebooting the router. It's completely random. Sometimes I get a day sometimes 5 minutes. I'm not able to ping it or log in via the web interface I have to go out in the garage and physically switch it off and and to reboot it.
I'm new to this fw, I need help troubleshooting it. Worst case I need to know how to out the stock fw back on. I tried to do it from the web interface and when it reboots it comes back to openwrt.
Thanks
Crashing is not normal for OpenWrt.... there are a number of things that could cause this, though... let's start by looking at the config:
Please connect to your OpenWrt device using ssh and copy the output of the following commands and post it here using the "Preformatted text </> " button (red circle; this works best in the 'Markdown' composer view in the blue oval):
Remember to redact passwords, VPN keys, MAC addresses and any public IP addresses you may have:
ubus call system board
cat /etc/config/network
cat /etc/config/wireless
cat /etc/config/dhcp
cat /etc/config/firewall
slh
October 24, 2025, 8:32pm
3
Good that ZyXEL has only manufactured a single router in 36 years…
1 Like
root@OpenWrt:~# ubus call system board
{
"kernel": "6.6.104",
"hostname": "OpenWrt",
"system": "ARMv7 Processor rev 0 (v7l)",
"model": "Zyxel NBG6817",
"board_name": "zyxel,nbg6817",
"rootfs_type": "squashfs",
"release": {
"distribution": "OpenWrt",
"version": "24.10.3",
"revision": "r28872-daca7c049b",
"target": "ipq806x/generic",
"description": "OpenWrt 24.10.3 r28872-daca7c049b",
"builddate": "1758316778"
}
}
root@OpenWrt:~# cat /etc/config/network
config interface 'loopback'
option device 'lo'
option proto 'static'
option ipaddr '127.0.0.1'
option netmask '255.0.0.0'
config globals 'globals'
option ula_prefix 'fd82:2a2a:e15e::/48'
option packet_steering '1'
config device
option name 'br-lan'
option type 'bridge'
list ports 'lan1'
list ports 'lan2'
list ports 'lan3'
list ports 'lan4'
config device
option name 'lan1'
option macaddr '<removed>'
config device
option name 'lan2'
option macaddr '<removed>'
config device
option name 'lan3'
option macaddr '<removed>'
config device
option name 'lan4'
option macaddr '<removed>'
config interface 'lan'
option device 'br-lan'
option proto 'static'
option ipaddr '192.168.1.2'
option netmask '255.255.255.0'
option ip6assign '60'
option gateway '192.168.1.1'
list dns '192.168.1.26'
list dns '8.8.8.8'
config device
option name 'wan'
option macaddr '<removed>'
config interface 'wan'
option device 'wan'
option proto 'dhcp'
config interface 'wan6'
option device 'wan'
option proto 'dhcpv6'
root@OpenWrt:~# cat /etc/config/wireless
config wifi-device 'radio0'
option type 'mac80211'
option path 'soc/1b700000.pci/pci0001:00/0001:00:00.0/0001:01:00.0'
option band '2g'
option channel 'auto'
option cell_density '0'
option country 'US'
option disabled '0'
config wifi-iface 'default_radio0'
option device 'radio0'
option network 'lan'
option mode 'ap'
option ssid 'OpenWrt'
option encryption 'none'
option disabled '1'
config wifi-device 'radio1'
option type 'mac80211'
option path 'soc/1b500000.pci/pci0000:00/0000:00:00.0/0000:01:00.0'
option band '5g'
option channel '36'
option htmode 'VHT80'
option cell_density '0'
option disabled '0'
config wifi-iface 'default_radio1'
option device 'radio1'
option network 'lan'
option mode 'ap'
option ssid 'OpenWrt'
option encryption 'none'
option disabled '1'
config wifi-iface 'wifinet2'
option device 'radio0'
option mode 'ap'
option ssid '<removed>'
option encryption 'sae-mixed'
option key '<removed>'
option ocv '0'
option network 'lan'
config wifi-iface 'wifinet3'
option device 'radio1'
option mode 'ap'
option ssid '<removed>'
option encryption 'psk2'
option network 'lan'
option key '<removed>'
root@OpenWrt:~# cat /etc/config/dhcp
config dnsmasq
option domainneeded '1'
option localise_queries '1'
option rebind_protection '1'
option rebind_localhost '1'
option local '/lan/'
option domain 'lan'
option expandhosts '1'
option cachesize '1000'
option readethers '1'
option leasefile '/tmp/dhcp.leases'
option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
option localservice '1'
option ednspacket_max '1232'
config dhcp 'lan'
option interface 'lan'
option start '100'
option limit '150'
option leasetime '12h'
option dhcpv4 'server'
option dhcpv6 'server'
option ra 'server'
list ra_flags 'managed-config'
list ra_flags 'other-config'
option ignore '1'
config dhcp 'wan'
option interface 'wan'
option ignore '1'
config odhcpd 'odhcpd'
option maindhcp '0'
option leasefile '/tmp/hosts/odhcpd'
option leasetrigger '/usr/sbin/odhcpd-update'
option loglevel '4'
root@OpenWrt:~# cat /etc/config/firewall
config defaults
option syn_flood 1
option input REJECT
option output ACCEPT
option forward REJECT
# Uncomment this line to disable ipv6 rules
# option disable_ipv6 1
config zone
option name lan
list network 'lan'
option input ACCEPT
option output ACCEPT
option forward ACCEPT
config zone
option name wan
list network 'wan'
list network 'wan6'
option input REJECT
option output ACCEPT
option forward REJECT
option masq 1
option mtu_fix 1
config forwarding
option src lan
option dest wan
# We need to accept udp packets on port 68,
# see https://dev.openwrt.org/ticket/4108
config rule
option name Allow-DHCP-Renew
option src wan
option proto udp
option dest_port 68
option target ACCEPT
option family ipv4
# Allow IPv4 ping
config rule
option name Allow-Ping
option src wan
option proto icmp
option icmp_type echo-request
option family ipv4
option target ACCEPT
config rule
option name Allow-IGMP
option src wan
option proto igmp
option family ipv4
option target ACCEPT
# Allow DHCPv6 replies
# see https://github.com/openwrt/openwrt/issues/5066
config rule
option name Allow-DHCPv6
option src wan
option proto udp
option dest_port 546
option family ipv6
option target ACCEPT
config rule
option name Allow-MLD
option src wan
option proto icmp
option src_ip fe80::/10
list icmp_type '130/0'
list icmp_type '131/0'
list icmp_type '132/0'
list icmp_type '143/0'
option family ipv6
option target ACCEPT
# Allow essential incoming IPv6 ICMP traffic
config rule
option name Allow-ICMPv6-Input
option src wan
option proto icmp
list icmp_type echo-request
list icmp_type echo-reply
list icmp_type destination-unreachable
list icmp_type packet-too-big
list icmp_type time-exceeded
list icmp_type bad-header
list icmp_type unknown-header-type
list icmp_type router-solicitation
list icmp_type neighbour-solicitation
list icmp_type router-advertisement
list icmp_type neighbour-advertisement
option limit 1000/sec
option family ipv6
option target ACCEPT
# Allow essential forwarded IPv6 ICMP traffic
config rule
option name Allow-ICMPv6-Forward
option src wan
option dest *
option proto icmp
list icmp_type echo-request
list icmp_type echo-reply
list icmp_type destination-unreachable
list icmp_type packet-too-big
list icmp_type time-exceeded
list icmp_type bad-header
list icmp_type unknown-header-type
option limit 1000/sec
option family ipv6
option target ACCEPT
config rule
option name Allow-IPSec-ESP
option src wan
option dest lan
option proto esp
option target ACCEPT
config rule
option name Allow-ISAKMP
option src wan
option dest lan
option dest_port 500
option proto udp
option target ACCEPT
### EXAMPLE CONFIG SECTIONS
# do not allow a specific ip to access wan
#config rule
# option src lan
# option src_ip 192.168.45.2
# option dest wan
# option proto tcp
# option target REJECT
# block a specific mac on wan
#config rule
# option dest wan
# option src_mac 00:11:22:33:44:66
# option target REJECT
# block incoming ICMP traffic on a zone
#config rule
# option src lan
# option proto ICMP
# option target DROP
# port redirect port coming in on wan to lan
#config redirect
# option src wan
# option src_dport 80
# option dest lan
# option dest_ip 192.168.16.235
# option dest_port 80
# option proto tcp
# port redirect of remapped ssh port (22001) on wan
#config redirect
# option src wan
See my reply before
{
"kernel": "6.6.104",
"hostname": "OpenWrt",
"system": "ARMv7 Processor rev 0 (v7l)",
"model": "Zyxel NBG6817",
"board_name": "zyxel,nbg6817",
"rootfs_type": "squashfs",
"release": {
"distribution": "OpenWrt",
"version": "24.10.3",
"revision": "r28872-daca7c049b",
"target": "ipq806x/generic",
"description": "OpenWrt 24.10.3 r28872-daca7c049b",
"builddate": "1758316778"
}
}
The config looks fine, the only suggestion I would make is that you should be using WPA2 (psk2) or WPA3 (sae) and not sae-mixed for your wifi encryption. Mixed mode doesn't always work well (as a function of client devices).
As for the crashing:
Make sure that you don't have an IP address conflict with other devices on the network (192.168.1.2)
Check your power supply -- you may have a failing power adapter. Replacing it can sometimes solve these issues.
Check to make sure the device is not getting hot and has adequate cooling/airflow.
If those don't solve the issue, you likely have a deeper hardware issue.
brada4
October 24, 2025, 8:46pm
9
Please show output of nft -t -s list ruleset replacing all IP addresses seen with ABC
There is nothing wrong shown so far. 24.10.4 is the latest and best stable release, but will not have any impact on your router problem.
AceMilo
October 24, 2025, 8:48pm
10
OK I will try that. Also, when it's crashed the 2 wifi lights will blink continuously in unisen. Is that anything?
slh
October 24, 2025, 8:50pm
11
ipq806x is not exactly without problems recently (for quite a while already, actually), it's not quite clear what exactly is the main issue at the moment, but you have a quite complex setup (multiple VLANs, multiple AP interfaces) -which is totally fine- that can contribute to triggering the underlying issue. If you can test a near-default install for a couple of days, that might provide a better handle.
AceMilo
October 24, 2025, 8:52pm
12
I shouldn't have any vlans installed. All I did was turn off the default openwrt wireless configs and change them to mine, turn it into an ap, and tell it where my dhcp router is.
brada4
October 24, 2025, 8:54pm
13
Normally OpenWrt boots at 20-few MB then uses ess than a MB per wifi client and few kB per wired.
AceMilo
October 24, 2025, 8:58pm
14
table inet fw4 {
chain input {
type filter hook input priority filter; policy drop;
iif "lo" accept comment "!fw4: Accept traffic from loopback"
ct state vmap { established : accept, related : accept } comment "!fw4: Handle inbound flows"
tcp flags & (fin | syn | rst | ack) == syn jump syn_flood comment "!fw4: Rate limit TCP syn packets"
iifname "br-lan" jump input_lan comment "!fw4: Handle lan IPv4/IPv6 input traffic"
iifname "wan" jump input_wan comment "!fw4: Handle wan IPv4/IPv6 input traffic"
jump handle_reject
}
chain forward {
type filter hook forward priority filter; policy drop;
ct state vmap { established : accept, related : accept } comment "!fw4: Handle forwarded flows"
iifname "br-lan" jump forward_lan comment "!fw4: Handle lan IPv4/IPv6 forward traffic"
iifname "wan" jump forward_wan comment "!fw4: Handle wan IPv4/IPv6 forward traffic"
jump handle_reject
}
chain output {
type filter hook output priority filter; policy accept;
oif "lo" accept comment "!fw4: Accept traffic towards loopback"
ct state vmap { established : accept, related : accept } comment "!fw4: Handle outbound flows"
oifname "br-lan" jump output_lan comment "!fw4: Handle lan IPv4/IPv6 output traffic"
oifname "wan" jump output_wan comment "!fw4: Handle wan IPv4/IPv6 output traffic"
}
chain prerouting {
type filter hook prerouting priority filter; policy accept;
iifname "br-lan" jump helper_lan comment "!fw4: Handle lan IPv4/IPv6 helper assignment"
}
chain handle_reject {
meta l4proto tcp reject with tcp reset comment "!fw4: Reject TCP traffic"
reject comment "!fw4: Reject any other traffic"
}
chain syn_flood {
limit rate 25/second burst 50 packets return comment "!fw4: Accept SYN packets below rate-limit"
drop comment "!fw4: Drop excess packets"
}
chain input_lan {
jump accept_from_lan
}
chain output_lan {
jump accept_to_lan
}
chain forward_lan {
jump accept_to_wan comment "!fw4: Accept lan to wan forwarding"
jump accept_to_lan
}
chain helper_lan {
}
chain accept_from_lan {
iifname "br-lan" counter accept comment "!fw4: accept lan IPv4/IPv6 traffic"
}
chain accept_to_lan {
oifname "br-lan" counter accept comment "!fw4: accept lan IPv4/IPv6 traffic"
}
chain input_wan {
meta nfproto ipv4 udp dport 68 counter accept comment "!fw4: Allow-DHCP-Renew"
icmp type echo-request counter accept comment "!fw4: Allow-Ping"
meta nfproto ipv4 meta l4proto igmp counter accept comment "!fw4: Allow-IGMP"
meta nfproto ipv6 udp dport 546 counter accept comment "!fw4: Allow-DHCPv6"
ip6 saddr fe80::/10 icmpv6 type . icmpv6 code { mld-listener-query . 0, mld-listener-report . 0, mld-listener-done . 0, mld2-listener-report . 0 } counter accept comment "!fw4: Allow-MLD"
icmpv6 type { destination-unreachable, time-exceeded, echo-request, echo-reply, nd-router-solicit, nd-router-advert } limit rate 1000/second burst 5 packets counter accept comment "!fw4: Allow-ICMPv6-Input"
icmpv6 type . icmpv6 code { packet-too-big . 0, parameter-problem . 0, nd-neighbor-solicit . 0, nd-neighbor-advert . 0, parameter-problem . 1 } limit rate 1000/second burst 5 packets counter accept comment "!fw4: Allow-ICMPv6-Input"
jump reject_from_wan
}
chain output_wan {
jump accept_to_wan
}
chain forward_wan {
icmpv6 type { destination-unreachable, time-exceeded, echo-request, echo-reply } limit rate 1000/second burst 5 packets counter accept comment "!fw4: Allow-ICMPv6-Forward"
icmpv6 type . icmpv6 code { packet-too-big . 0, parameter-problem . 0, parameter-problem . 1 } limit rate 1000/second burst 5 packets counter accept comment "!fw4: Allow-ICMPv6-Forward"
meta l4proto esp counter jump accept_to_lan comment "!fw4: Allow-IPSec-ESP"
udp dport 500 counter jump accept_to_lan comment "!fw4: Allow-ISAKMP"
jump reject_to_wan
}
chain accept_to_wan {
meta nfproto ipv4 oifname "wan" ct state invalid counter drop comment "!fw4: Prevent NAT leakage"
oifname "wan" counter accept comment "!fw4: accept wan IPv4/IPv6 traffic"
}
chain reject_from_wan {
iifname "wan" counter jump handle_reject comment "!fw4: reject wan IPv4/IPv6 traffic"
}
chain reject_to_wan {
oifname "wan" counter jump handle_reject comment "!fw4: reject wan IPv4/IPv6 traffic"
}
chain dstnat {
type nat hook prerouting priority dstnat; policy accept;
}
chain srcnat {
type nat hook postrouting priority srcnat; policy accept;
oifname "wan" jump srcnat_wan comment "!fw4: Handle wan IPv4/IPv6 srcnat traffic"
}
chain srcnat_wan {
meta nfproto ipv4 masquerade comment "!fw4: Masquerade IPv4 wan traffic"
}
chain raw_prerouting {
type filter hook prerouting priority raw; policy accept;
}
chain raw_output {
type filter hook output priority raw; policy accept;
}
chain mangle_prerouting {
type filter hook prerouting priority mangle; policy accept;
}
chain mangle_postrouting {
type filter hook postrouting priority mangle; policy accept;
oifname "wan" tcp flags & (fin | syn | rst) == syn tcp option maxseg size set rt mtu comment "!fw4: Zone wan IPv4/IPv6 egress MTU fixing"
}
chain mangle_input {
type filter hook input priority mangle; policy accept;
}
chain mangle_output {
type route hook output priority mangle; policy accept;
}
chain mangle_forward {
type filter hook forward priority mangle; policy accept;
iifname "wan" tcp flags & (fin | syn | rst) == syn tcp option maxseg size set rt mtu comment "!fw4: Zone wan IPv4/IPv6 ingress MTU fixing"
}
}
brada4
October 24, 2025, 9:33pm
15
again nothing wrong.
Connect using ssh and run logread -f in that session and wait for it to crash again. There is a chance what happens last is logged this way.
1 Like
AceMilo
October 25, 2025, 10:51am
16
It crashed again overnight. I'd like to revert back to stock fw. How do I do that?
AceMilo
October 25, 2025, 11:37am
17
It appears it is no longer booting at all. The lights come on and blink but I cannot ping it and cannot join the wifi. I don't know what to do.
_bernd
October 25, 2025, 12:06pm
18
AceMilo
October 25, 2025, 12:19pm
19
Thanks but I don't see anything there about going back to oem firmware.
AceMilo
October 25, 2025, 12:23pm
20
I've done a factory reset and redid my configuration from scratch. Let's see what happens.
brada4
October 25, 2025, 12:57pm
21
Please install zram-swap package to contain eventual memory leaks, and owut and/or luci-app-attendedsysupgrade for future upgraades
AceMilo
October 25, 2025, 2:01pm
22
OK how do I do that? If I go to software the list is empty and if I say update list is can't download anything. If I ssh into the router I can ping out to the internet fine.
