LTE with Huawei B818 > OpenWRT Packageloss

hefegraphie · May 27, 2025, 12:11pm

Hey, I’ve been using OpenWrt for 3 years now and I love it.

My DSL contract is ending in July, and I don’t want to renew it because Deutsche Glasfaser is coming later this year. In the meantime, I wanted to use LTE, since I have a MultiSIM with unlimited data and good speeds here.

Unfortunately, I'm going crazy with the configuration.

B818 in bridge mode to WAN of OpenWrt
B818 with DMZ to OpenWrt (2 subnets)
B818 with double NAT to OpenWrt (2 subnets)
B818 as router and OpenWrt as DHCP server (in the same subnet) – This is the least thing I want, because I have more than 100 devices in my network.

On the WAN side, I reduced the MTU to 1472 and enabled MSS clamping.

I tried two different devices as “partners” for the B818: a Xiaomi Mi Router 4A Gigabit Edition and an ASUS Nighthawk 7200.
Same results: packet loss and timeouts when pinging 1.1.1.1 or 8.8.8.8 or other sites.
In daily usage, this shows up as high latency and websites not being reachable for minutes at a time.

I have multiple access points, but I don't think they’re the issue—because if I switch back to DSL, everything runs like a charm.
The only difference is that Telekom DSL uses PPPoE.

Anyway I must be doing something wrong in configuration (especialy in IPv4?), because i recogniced by accident yesterday, that my phone worked like a charm in the configuration "B818 as router and OpenWrt as DHCP server (in the same subnet)" but recogniced later, that this was maybe because it ran in ipv6. My PC witch was only ipv4, had the same Problems as always.

brada4 · May 27, 2025, 1:53pm

Common element seems to be the cable???

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:

Remember to redact passwords, 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

hefegraphie · May 27, 2025, 2:11pm


root@Gaestezimmer:~# ubus call system board
{
        "kernel": "5.15.162",
        "hostname": "Gaestezimmer",
        "system": "MediaTek MT7621 ver:1 eco:3",
        "model": "Xiaomi Mi Router 4A Gigabit Edition",
        "board_name": "xiaomi,mi-router-4a-gigabit",
        "rootfs_type": "squashfs",
        "release": {
                "distribution": "OpenWrt",
                "version": "23.05.4",
                "revision": "r24012-d8dd03c46f",
                "target": "ramips/mt7621",
                "description": "OpenWrt 23.05.4 r24012-d8dd03c46f"
        }
}
root@Gaestezimmer:~# 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 packet_steering '1'
        option ula_prefix 'fd71:4314:d83a::/48'

config device
        option name 'br-lan'
        option type 'bridge'
        list ports 'lan1'
        list ports 'lan2'

config interface 'lan'
        option device 'br-lan'
        option proto 'static'
        option ipaddr '192.168.178.1'
        option netmask '255.255.255.0'
        option force_link '0'
        option defaultroute '0'
        option ipv6 '0'

config interface 'Wan'
        option proto 'dhcp'
        option device 'wan'

config device
        option name 'wan'
        option mtu '1472'

root@Gaestezimmer:~# cat /etc/config/wireless

config wifi-device 'radio0'
        option type 'mac80211'
        option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0'
        option channel '1'
        option band '2g'
        option cell_density '0'
        option txpower '20'
        option htmode 'HT20'

config wifi-device 'radio1'
        option type 'mac80211'
        option path '1e140000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
        option channel '36'
        option band '5g'
        option htmode 'VHT80'
        option cell_density '0'
        option disabled '1'

config wifi-iface 'wifinet0'
        option device 'radio0'
        option mode 'ap'
        option ssid 'retracted'
        option encryption 'psk2'
        option key 'retracted'
        option ieee80211r '1'
        option mobility_domain '2101'
        option ft_over_ds '0'
        option ft_psk_generate_local '1'
        option network 'lan'
        option disabled '1'

config wifi-iface 'wifinet1'
        option device 'radio1'
        option mode 'ap'
        option ssid 'retracted'
        option encryption 'psk2'
        option key 'retracted'
        option ieee80211r '1'
        option mobility_domain '2101'
        option ft_over_ds '0'
        option ft_psk_generate_local '1'
        option network 'lan'
        option disabled '1'

config wifi-iface 'wifinet2'
        option device 'radio1'
        option mode 'ap'
        option ssid 'retracted'
        option encryption 'psk2'
        option key 'retracted'
        option ieee80211r '1'
        option mobility_domain '2102'
        option ft_over_ds '0'
        option ft_psk_generate_local '1'
        option network 'lan'
        option disabled '1'

config wifi-iface 'wifinet3'
        option device 'radio0'
        option mode 'ap'
        option ssid 'Opentest'
        option encryption 'psk2'
        option key 'retracted'
        option network 'lan'

root@Gaestezimmer:~# cat /etc/config/dhcp

config dnsmasq
        option domainneeded '1'
        option boguspriv '1'
        option filterwin2k '0'
        option localise_queries '1'
        option rebind_protection '1'
        option rebind_localhost '1'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option nonegcache '0'
        option authoritative '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
        option nonwildcard '1'
        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 'disabled'
        option ra 'disabled'

config odhcpd 'odhcpd'
        option maindhcp '0'
        option leasefile '/tmp/hosts/odhcpd'
        option leasetrigger '/usr/sbin/odhcpd-update'
        option loglevel '4'

root@Gaestezimmer:~# cat /etc/config/firewall

config defaults
        option input 'ACCEPT'
        option output 'ACCEPT'
        option forward 'REJECT'
        option synflood_protect '1'

config zone
        option name 'lan'
        option input 'ACCEPT'
        option output 'ACCEPT'
        option forward 'ACCEPT'
        list network 'lan'

config zone
        option name 'wan'
        option input 'REJECT'
        option output 'ACCEPT'
        option forward 'REJECT'
        option masq '1'
        option mtu_fix '1'
        list network 'Wan'

config forwarding
        option src 'lan'
        option dest 'wan'

config rule
        option name 'Allow-DHCP-Renew'
        option src 'wan'
        option proto 'udp'
        option dest_port '68'
        option target 'ACCEPT'
        option family 'ipv4'

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'

config rule
        option name 'Allow-DHCPv6'
        option src 'wan'
        option proto 'udp'
        option src_ip 'fc00::/6'
        option dest_ip 'fc00::/6'
        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'

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'

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'

config rule
        option name 'Support-UDP-Traceroute'
        option src 'wan'
        option dest_port '33434:33689'
        option proto 'udp'
        option family 'ipv4'
        option target 'REJECT'
        option enabled 'false'

config include
        option path '/etc/firewall.user'

config zone
        option name 'WRK'
        option input 'ACCEPT'
        option output 'ACCEPT'
        option forward 'ACCEPT'

The Huawei has configured a static lease for 192.168.8.2 to the router. And a DMZ is set to the IP too.
DHCP is swiched on on the B818. But this is a different subnet and the range starts at 192.168.8.100...
So i hope this is not a problem

AndrewZ · May 27, 2025, 2:20pm

Connect your PC directly to Huawei device (in a bridge mode) and discover the MTU as shown here. Share the final result.
Please correct the topic title.

hefegraphie · May 27, 2025, 2:36pm

Thank you, I did it already and repeated now.

1472 is the MTU befor it gets fragmented (28 not added)

how should the threadtitle be?

brada4 · May 27, 2025, 2:42pm

23.05.4 is defec%ive - it switches antennas to 1x1 without reason. Install luci-app-attendedsysupgrade and get to.5 and re-test

hefegraphie · May 27, 2025, 5:33pm

Thank you

I updated All openwrt Devices to 24.10.1.

First i Thought it did it.
But after 30 Minutes started timout. After 45 Minutes no connection to Internet was possible.

Edit: i unplugged the wire to which connects the openwrt Router to my network. Only b818 and Router left alone.
Now, after one hour i connected to the Router with the Phone via WiFi.
Great Internet connection. No Problem.
Do i have to Many Devices in my Network for lte or the b818 (which is in bridge mode right now)

hefegraphie · May 28, 2025, 2:04pm

I reply to myself.
I ran the router over night Standalone with the Openwrt AP's and a switch in between.
Connection was stable and good.

So i had the Idea to keep it that way and implement one of the Openwrt Router as DHCP.
Still worked.

So the problem seemed to be that my config of the devices was this:

The AP with DHCP was maybe some kind of a bottleneck.

this way everything runs like a charm:

To be honest i do not understand why, because the DHCP AP did not route. But this solved the problem.

system · June 7, 2025, 2:04pm

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