Debian11 VM cannot ping gateway, but can ping Proxmox hypervisor through linux-bridge

[Yanux]

I am encountering a network issue with linux-bridge in a small Proxmox cluster lab.
I have a Debian11 VM installed that can't ping the gateway, but can ping the Proxmox hypervisor.
The hypervisor uses the same bridge as the VM to be reachable.

The routes of the VM and hypervisor seem to be OK.

Debian IP: 192.168.3.240/24 via ens18 (card connected to vmbr0)
Hypervisor IP: 192.168.3.231/24 (indicated in vmbr0 configuration)
Gateway IP: 192.168.3.1/24

192.168.3.231 => 192.168.3.1: OK
192.168.3.240 => 192.168.3.231: OK
192.168.3.240 => 192.168.3.1: NOT OK

Proxmox hypervisor configuration:
/etc/network/interfaces :

auto lo
iface lo inet loopback

auto enp0s3
iface enp0s3 inet manual

auto enp0s8
iface enp0s8 inet manual

auto enp0s9
iface enp0s9 inet manual

auto enp0s10
iface enp0s10 inet manual

auto bond2
iface bond2 inet static
        address 192.168.10.2/24
        bond-slaves enp0s10 enp0s9
        bond-miimon 100
        bond-mode balance-rr
#CEPH

auto vmbr0
iface vmbr0 inet static
        address 192.168.3.231/24
        gateway 192.168.3.1
        bridge-ports enp0s3
        bridge-stp off
        bridge-fd 0

edit routage :

brctl show: 
bridge name     bridge id               STP enabled     interfaces
vmbr0           8000.08002701da38       no              enp0s3

 

[B.Otto]

These IPs are all in the same subnet, so there is no routing necessary. The config looks good too. Bridges operate on Layer2, so if the Pings VM->vmbr0 and Proxmox->Gateway work, then VM->Gateway should also work... Maybe there is something with your Gateway, like Firewall settings blocking traffic (or just ICMP) from unknown addresses?

 

[rthm]

These IPs are all in the same subnet, so there is no routing necessary. The config looks good too. Bridges operate on Layer2, so if the Pings VM->vmbr0 and Proxmox->Gateway work, then VM->Gateway should also work... Maybe there is something with your Gateway, like Firewall settings blocking traffic (or just ICMP) from unknown addresses?

I am facing the same issue, how do I find out what is causing this?