[kwlug-disc] Puzzling network issue ...

[Chris Frey]

On Thu, Nov 20, 2025 at 08:42:35PM -0500, Khalid Baheyeldin wrote:
> The issue does not seem to be a firewall issue, because I have not changed
> that at all, and I do see responses, but no traffic.

Track down what did change.  Check for package upgrades.  Do things
get updated automatically?  What packages updated in the past few days?


> But when I go to that URL, the browser (or curl) hangs there indefinitely.
> 
> $ curl s1.example.com:3000/login # Grafana, Hangs
> 
> $ curl s1.example.com:8123/ # Home Assistant, Hangs

Try a tcpdump on both sides of the wireguard connection to see
if packets are getting lost.

On each side, try 'ip route get' to diagnose where the packets would go,
in both directions.

> I restarted the Wireguard tunnels on both machines, just in case:
> 
> $ sudo systemctl status wg-quick at wg0
> 
> And it made no difference.

Have you tried the drastic action of a reboot?


> This is happening for various services, but only from specific machines,
> but not others.

Get tcpdump logs from the working machines and compare with the broken
ones, along with what the server side sees too, on the wireguard
iface and the webserver iface (if different).

Hope that helps,
- Chris