Can't receive Duo Auth Push Notification on Mobile because of Synology Firewall

[thibaudbrg]

Hello, I'm trying to implement Authelia auth correctly with the two-factor authentification Duo Auth.
Traefik, Authelia and everything else are running on my DS920+ Synology with docker.

During my tests, I disable momentarily the Synology integrated firewall. In this case, everything's working fine. Thanks to my authelia middleware, I have the login page before accessing any site. I login with my credentials and then use the two-factor authentification Duo Auth. I receive the push notif on my phone, check ok and we're good.

But when reactivating the firewall, I do not receive the push notification to my phone.
I have already open the ports 9091, 587 (for mail-notifier) but I don't find the one for the push notif on my phone.

Regarding the logs it seems that each time Duo sends a request to my phone, it uses a completely new random port.

Does anyone find a the port? or a way to get around the problem?