I have ProxMox 5.1 setup on an IBM x3550 M3 machine. Using /etc/network/interfaces I have given the machine IP address 192.168.50.71, and a bridge address of 192.168.50.110. It is connected to a switch dedicated to the 192.168.50.x network. My PC (ip 10.10.10.150) is on a seperate switch, dedicated to the 10.10.10.x network. Both the 10.10.10.x switch and the 192.168.50.x switched are plugged into the same firewall. The ProxMox machine can be pinged by any machine on the 192.168.50.x network, and my machine on the 10.10.10.x network can ping any machine on the 192.168.50.x network EXCEPT for the Proxmox machine. I tried turning off the pve-firewall service, and no change. I tried plugging in a laptop using the same cable from the ProxMox machine and changed it's ip address to 192.168.50.71 and my machine can now ping the IP address. So it appears that something in ProxMox is allowing communication from the same 192.168.50 network, but not from the 10.10.10.x network. Any ideas on what is stopping it from talking to the other network, and/or how to fix it?