From your post we can not help. There is no question at all  ;-)
Please start by giving us some more information, like the copy-n-pasted output of some commands, run on a PVE host (either via SSH or via "Datacenter --> <one Node> --> Shell", both ways allow copy-n-paste):
PVE System information:
Basic network information:
-         ip address show                 # currently active IP addresses on one NODE
-         ip route show                   # currently active routing table on one NODE
-         ip link show                    # currently active links on one NODE
-         cat /etc/network/interfaces     # configuration of the network     and/orifquery -afor comparison from one NODE
-         cat /etc/resolv.conf            # DNS resolver settings
-         ping -c 1  -W 1  9.9.9.9        # a simple "ping" to verify outgoing routing
-         host quad9.net                  # a simple DNS lookup to verify reachable DNS servers
Problematic VM:
-         export VMID=<the_ID_of_the_VM>;  qm config --current true  ${VMID}# the configuration of that VM
And from 
inside that VM, Basic network information:
-             ip address show                 # currently active IP addresses
-             ip route show                   # currently active routing table
-             cat /etc/network/interfaces     # Debian et all
-            head -n -0 /etc/netplan/*       # Ubuntu
Those are examples. You may add/edit commands and options if you can enrich the information given. Oh, and please put each command in a separate 
[CODE]...[/CODE]-block for better readability.