Network requirements for Talk notifications

Good morning. I have a question about the specific network requirements to have push notifications working in Nextcloud Talk.

I block non-ARIN IPs in my firewall for added security. I want to make sure this isn’t interfering with push notifications. I have seen some references to and, which are not ARIN IPs, but little to no info about whether these need to be unblocked and on what port(s).

I was having issues with not getting notifications. I have since allowed those two FQDNs in my firewall, and the notifications were working again. I would like to know the specific network requirements so I can keep it as locked down as possible but not inadvertently block something that is needed.