No Push notifications on Android when connected to WLAN?

[vsatmydynipnet]

Good Morning, is there a known problem, that Andoird Users, using GPlay Version, even the one from yesterday, does not (or receive with a long delay) receive Push Notifications? I have complaints of different users of the HS that they have problems with it. Not connected to WLAN, e.g. LTE push notifications works fine. This is very annoying to them and I hope there is a solutions or workaround.

• Different Users in different WLAN Networks
• Users use the same HS
• Their HS is running on Yunohost (Synapse 1.65.0)

[ruben-tura]

Same thing here. I actually didn't notice that on mobile network it was fine, but it is. Weird.

[ouchadam]

Is it possible that the WLAN networks are running firewalls? We've seen issues in the past with pi-hole blocking the firebase push urls