I want to flash my Zyxel NBG6817 which is unused and a backup router.
It should have the IP 192.168.178.12 (written down), but maybe this is wrong.
Before I flashed a similar Netgear X4S-R7800 and now I try to connect the same way, but get no connection.
I use a minipc using Xubuntu 26.04. Nm-applet disabled wifi, so the only connection should be the enternet cable.. The minipc has only 1 ethernet, so there cannot be other devices be reachable, except via wifi and this is disabled.
IPv4 is set to DHCP on the pc. It could be that DHCP is disabled at the Zyxel. I assume the Zyxel runs openwrt 23.
What can I try to get a connection?
I am pretty sure, that the Zyxel is configured with the Fritzbox network. I can't believe that I didn't change the network. But there might be a chance that it has the IP after flashing openwrt.
Should it matter which network the router has configured, when there is only 1 Ethernet connection with automatic DHCP on the pc side?
Strange, maybe I have a weird pc. Yesterday there have been also strange problemes with a Netgear. Maybe arp-cache is fooling me.
I connected the router now to a LAN port of my main openwrt-router and did a network scan with my phone and I see
I could login via Wifi connection, but it disappeared after a night and I saw the Zyxel now. Via an other pc, connected via Wifi too, I could login and see:
Model ZyXEL NBG6817
Architecture ARMv7 Processor rev 0 (v7l)
Target Platform ipq806x/generic
Firmware Version OpenWrt 23.05.3 r23809-234f1a2efa / LuCI openwrt-23.05 branch git-24.086.45142-09d5a38
Kernel Version 5.15.150
I did:
root@NBG6817:/tmp# sysupgrade -n /tmp/openwrt-25.12.5-66d4b5bfcf0e-ipq806x-gener
ic-zyxel_nbg6817-squashfs-sysupgrade.bin
Sat Jul 4 11:42:56 UTC 2026 upgrade: Commencing upgrade. Closing all shell sessions.
Command failed: Connection failed
root@NBG6817:/tmp# Connection to 192.168.178.12 closed by remote host.
Connection to 192.168.178.12 closed.
So the remaining question is now as asked above already: Should I get a connection to the minipc by just plugging it in? I know the Zyxel has now 192.168.1.1. I try to avoid a new install of the minipc.
Since the Zyxel has now the standard configuration where the DHCP server should be enabled, i'd say yes.
Why should that be necessary? Either set your network card on the pc to DHCP or set the IP to 192.168.1.[something between 2 and 254].
Because it could be, that something is broken with the pc. Yesterday no ssh connection in the fritzbox-net was possible with some devices, but not all. Today it worked without problems.
I try now to get a connection to the Zyxel with this minipc.
It's always a good idea to have a independent PC / notebook / RaspPi / whatever which is not part of your local network just for configuring network devices.
For this i've got a ~13 years old notebook, which i use mainly for configuration stuff (running linux of course).
Exactly and that is why I used this minipc.
I think there are multiple problems and one is DHCP.
2 DHCP servers are a bad idea, but maybe this is better for a short workaround. AFAIK there is some protection, that 2 IP addresses are not used.
I could connect to the minipc with 192.168.1.1 to the Zyxel, then I changed to 192.168.178.12 again and disabled DHCP and then there was no connection possible. I should have given the mini pc a manual static IP. I assume the Netgear had DHCP enabled, why it worked.
Then there is from time to time:.
** WARNING: connection is not using a post-quantum key exchange algorithm.
As a result I cannot get a ssh-connection. I hope this is gone with 25.12.5
Next problem was that scp to the Zyxel did not work and I got no error message. "scp -O" worked then With the Netgear I got a clear error message.
At the end everything works now as I want and I hope I will never have to configure this backup-router.
This should only be a warning and not prevent the connection.
Do you use busybox or openssh on your router?
I can't answer this anymore because everything works now with 25.12 and I don't know what was installed with openwrt 23. But I could not login and then I could after a few trials. That is so confusing, that something worked sometimes.
But at least a short test with 25.12.5 worked and the Zyxel is waiting if I need a backup hardware.