Losing access to IP addresses (incuding OPNSense WebUI)

[bbyrd]

I've had this happen for the second time in a week or now. Runinng OPNSense 25.1.12 on a HP T620+, everything has been running fine, and then I suddenly lose access to all IP addresses on the network, including the OPNSense box. By losing IP access, I mean web access to web GUIs at IP addresses (e.g. the OPNSense web UI, web-access to my Proxmox server, various local-hosted apps that I normally access by IP address) - they all time out. Likewise SSH access to the same - all time out.

Weirdly, my internet is still up from all devices (and strangely - this time at least (I don't think I had this last time) - so are the external domains that are internet facing for my apps (Jellyfin for example).

The OPNSense box is still providing DHCP (I can release and renew IP on a Windows machine and get an IP address), and DNS (via Adguard Home on the OPNSense box).

But... I can't access any IP addresses!

At first I thought the OPNSense box wasn't booting properly, so I pulled it from the rack and started it up in the office with monitor and keyboard access. All seemed to boot fine, could log in on the console - no issues I could see.

The last time this happened (about a week ago), I "fixed" it by booting a live USB of OPNSense, running opnsense-importer from the console and running from there. I'm about to try something like that again, but really want to understand what is happening here. There were no changes to the OPNSense box to trigger an issues. I have shutdown my main server around the same time to do some hardware changes, but it's back up and running fine (I can't access it over the network, but it is serving up my apps and reverse proxy just fine - see above).

Any ideas from the brains trust, cos I'm tearing my hair out here?

[bbyrd]

After seeing that I seem to get access back after a reboot, I wondered is something starting up on my local machine could be causing this issue. As it turns out, yes!

When Tailscale started up, it was blocking access to local ports. As I run Tailscale on most of my machines with automatic start, this was affecting multiple machines a minute or so after startup. Only realised this was an issue when I suddenly had access to IPs after a Windows update and reboot (and noticed that an "Error - connection change" was booting me off again). Partly caused by the Tailscale connection on my server (which enables access to subnets) not starting automatically.