Problem accessing Proxmox GUI on remote site connected via Wireguard

[sprickw]

Yes, I did read the posts regarding Wireguard over here, but nothing seems to fit.

I connected two site with site-to-site wireguard, site A ist server, side B "client". Everything seems fine both directions. ping and ssh work. Even curl to the remote Proxmox GUI works:

curl -v http://192.168.0.201:8006
* Trying 192.168.0.201:8006...
* Connected to 192.168.0.201 (192.168.0.201) port 8006 (#0)
> GET / HTTP/1.1
> Host: 192.168.0.201:8006
> User-Agent: curl/7.81.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 301 Moved Permanently
< Cache-Control: max-age=0
< Connection: Keep-Alive
< Date: Thu, 15 Feb 2024 20:45:17 GMT
< Pragma: no-cache
< Location: https://192.168.0.201:8006/
< Server: pve-api-daemon/3.0
< Expires: Thu, 15 Feb 2024 20:45:17 GMT
* no chunk, no close, no size. Assume close to signal end
<
* Closing connection 0

But trying to connect to Proxmox GUI at site B with different browsers (Firefox, Chromium, Brave, Edge, Opera) get timeouts with http/https.

All firewalls at remote datacenter/Proxmox server are off.

Accessing the Proxmox server from local LAN works as expected. Even more weird: Access from site B to Proxmox GUI at site A works.

After spending a few hours on this I still have no idea.

Any hints?

Regards Wolfgang

 

[_gabriel]

it could be a non optimal MTU.
I have same problem with openvpn client over mobile connection where need to set mssfix 1400.
have you checked iperf3 speed in both direction ?
then follow https://gist.github.com/nitred/f16850ca48c48c79bf422e90ee5b9d95#file-optimal_mtu-md

edit: after more tests , even openvpn client on windows need mssfix 1400 , with default value sometimes RDP fails.

 

[sprickw]

it could be a non optimal MTU.
I have same problem with openvpn client over mobile connection.
(weird openvpn client on Windows works with default values, but openvpn client on Linux pve host need mssfix 1400)
have you checked iperf3 speed in both direction ?
then follow https://gist.github.com/nitred/f16850ca48c48c79bf422e90ee5b9d95#file-optimal_mtu-md

Thank you. Never thought of that, as its new to me. Will have a look into it.