Hey folks,

So I just completed a full motherboard replacement but can't get anything on the server to connect to any external services.
All docker containers fail to connect, DNS test times out and ping requests just hang. I can access the Web GUI from my desktop on the same network and previously booted the server up with monitor attached with GUI and was able to get to Google in a browser with no issues.

I've been searching for hours now and I'm thinking there's gotta be something critical I'm missing related to the new Ethernet interface, but I can't for the life of me figure it out.

I've:
- Removed all old DHCP listings in router and re-bound the IP,
- Deleted network.cfg
- Manually set Unraid DNS to Google & Cloudflare,
- No luck with the Fix Common Problems plugin other than the obvious "DNS settings wrong".

After about 4 hours of rebooting and testing, I finally had some luck after setting a new static IP in the router.
For some reason it just won't work on 192.168.0.100 anymore. It was working fine before the mobo change over, but no idea why it's having issues now.

Diagnostics zip plus Syslog attached - if anyone can tell me what is causing the issue so I can solve it in future that would be greatly appreciated!

khazad-dum-diagnostics-20260713-2313.zip syslog-192.168.0.100.log

Edited July 13Jul 13 by KuristZero

1. disable bonding for now

2. reboot your router, it seems like the IP address you assigned it is in use by another device or being assigned twice.

Jul 13 22:55:15 Khazad-dum dhcpcd[1968]: br0: 10 second defence failed for 192.168.0.100
Jul 13 22:55:15 Khazad-dum dhcpcd[1968]: br0: deleting route to 192.168.0.0/24
Jul 13 22:55:15 Khazad-dum dhcpcd[1968]: br0: deleting default route via 192.168.0.1
Jul 13 22:55:15 Khazad-dum dhcpcd[1968]: br0: rebinding lease of 192.168.0.100
Jul 13 22:55:15 Khazad-dum dhcpcd[1968]: br0: probing address 192.168.0.100/24
Jul 13 22:55:19 Khazad-dum reload_services: execute queued job 27
Jul 13 22:55:21 Khazad-dum dhcpcd[1968]: br0: leased 192.168.0.100 for infinity
Jul 13 22:55:21 Khazad-dum dhcpcd[1968]: br0: adding route to 192.168.0.0/24
Jul 13 22:55:21 Khazad-dum dhcpcd[1968]: br0: adding default route via 192.168.0.1
Jul 13 22:55:21 Khazad-dum dhcpcd-run-hooks: interface=br0, reason=BOUND, protocol=dhcp

Something else you can try is delete the network.cfg and network-extra.cfg from the /boot/config folder and rebooting unraid to see if that clears this up.

An old mac address assigned to an ip address inside router could also cause trouble.

Thanks for the suggestions folks, I think I found it - hidden setting in the router. More info below!

Bonding
Good catch on the network bonding. I've turned that off for now, but this didn't resolve the issue when returning to the old IP (again, router side anyway).
Any particular reason to have this on or off? I've not touched Unraid's networking settings much outside of Cloudflare tunnels etc

Network.cfg
I did wipe the network.cfg as mentioned above, but was unaware of network-extra.cfg - is this meant to be in the config folder, as it's not appearing in mine? Is that a standard file or a potential extra that shows up?

Router side
Router has gone through several reboots too, and I removed the old static IP and MAC address from every setting I set them in while the server was powered down to prevent any accidental reservations.

HOWEVER the problem was an automatic setting that TP Link had auto-activated after I updated the routers firmware a year back (security issue in the code base, so needed the update). For anyone facing the same issue with a TP Link router:
Head to Advanced Settings > Security > ARP Binding (or IP & MAC binding depending on your router).

This was now turned on by default after the security update, probably as a "security feature" and had all the reserved IP addresses added from the DHCP reservation list.

Once I removed the old IP and MAC combo, we were back online!

Thanks so much for the suggestions and guidance folks!