[SOLVED] Proxmox 8.2.4 vs 8.2.7 networking issue

[dekkert]

I have two identical Proxmox Server working. Both with an public IP Adress 72.x.y.z used as Gateway and a wireguard Network server I 10.48.5.1/24 and server II 10.48.6.1/24.

There is an wireguard Network 10.48.0.0/16 in the background, connecting some server. works well.

First Server at 10.48.5.1, (Proxmox 8.2.4) with an windows Server virtual machine 10.48.5.10, gateway 10.48.5.1, and an external DNS-Server works well. I have connection between the VMs, to the VMs via the wireguard network and internet access to the whole world

"Same"(*) configuration on the Second Server 10.48.6.1 (Proxmox 8.2.7) did not work. It is not even possible to ping 8.8.8.8.

Any idea how to check, test, find the error? Thank you.

Best regards
Andraes

(*) I have checked, all the same (I think)
wireguard on the 10.48.5/6.1
Promox network settings
/etc/network/interfaces
/etc/iptables/rules.v4
Network settings in the Windows-Server-VM
Firewall settings in the Windows-Server-VM
DeviceManager Networking

 

[dekkert]

ChatGPT (our least expensive employee) says:
Look for net.ipv4.ip_forward = 1
And he is right.