HA in LXC Container Shelly devices failed to connect

[ILC0nte]

Hi,
I've installed HA as in subject on proxmox 7.3 and 7.2 and i've encountered a problem with the native shelly integration.
Shelly devices will not discovered and, trying to add them manually, they ends up with "Failed to connect" after the input of the shelly ip address.
I've tried to debug the issue doing a tcpdump but nothing seems to be wrong.
Mdns broadcast packets reach the container and upd port 5683 is open.
When i input the shelly ip address in the integration wizard ha connects to port 80 of the shelly, get the status and i can see the shelly response but then the process goes to time-out!
I've also tried the HaOS in VM installation and HA-CORE pure python installation in an LXC container but all ends with the same problem.
In the same network there is another PC with docker and another ha instance (the old hw that i need to replace btw) that works flawlessy.
My mind is that the problem is the proxmox network stack but i can't figure out what is wrong.
Other tests done:
Disable firewall
change container network mode (host, bridge)
Privileged and unprivileged container
App armor disabled
Downgrade from proxmox 7.3 to 7.2
Factory resetted shellyes

Someone else with same issue?