Wireguard no traffic no handshake

[fvs]

Hi everyone,
i need some help setting up a site-to-site tunnel using wireguard. I already set up a lot of them but after an entire day trying to fix this problem i am ko.
Both sides have WAN Rules with port 60300 (wireguard) open from every source to every destination.

SITE A:

Code Select Expand

[Interface]
PrivateKey = priv_key_site_A
Address = 10.20.0.7/24
ListenPort = 60300

[Peer]
PublicKey = pub_key_site_b
Endpoint = ip site b:60300
AllowedIPs = 10.20.0.6/32

SITE B:

Code Select Expand

[Interface]
PrivateKey = private_site_B
Address = 10.20.0.6/24
ListenPort = 60300

[Peer]
PublicKey = public_site_A
Endpoint = ip_site_A:60300
AllowedIPs = 10.20.0.7/32

If i try to reset wireguard from shell it doesn't return any error, in handshake tab i read the key followed by a zero on both sides.
If i open the firewall i have no traffic on wg interfaces.
I already assigned both wg interfaces on both sides, i activated them and enable prevent removal.
I don't know what i can do to solve this problem, thanks in advice

EDIT: on site B i already have another wireguard interface for another site-to-site and it works flawlessly.