no traffic between LXC containers

[mig84]

Dear all,
i am running Proxmox VE 8.0.4 on an Intel NUC NUC6CAYH and have a strange problem:
there are two LXC containers (created from debian-11-standard_11.7_1)
they are on the same subnet, same network assigned to them: vmbr0
they can be accessed from everywhere as expected and can reach internet and so on.
all fine.

BUT: they can´t reach each other. not even with ping.

container a does not have an entry in the ARP table for container b.
in tcpdump container a does not even generate ARP traffic to look for container b.

I am new to Proxmox, so maybe this is expected and just needs some configuration?

would be great if someone could help.

mig84

 

[Moayad]

Hi,

Have you checked the firewall?

 

[mig84]

Hi,

Have you checked the firewall?

Hi!

Firewall is disabled at datacenter level.

However, on the host its also turned off:
root@proxmox0:~# pve-firewall status
Status: disabled/stopped

Same for the lxc containers:
"Firewall: no"

What else can I check?

 

[Moayad]

May you please provide us with your network config?