VPN with Iphone and Fritzbox

Hello everyone,

I’ve been trying to establish a connection to my home network via my Iphone, but strangely sometimes I can get a ping from my PC in the home network to my IPhone sometimes not . I cannot access my router-Website nor any other ressources of my home network from my Iphone, even though it shows a little VPN-Icon here and then.

I also downloaded the ZeroTier-App on my PC, where the status of my network is noted as “ok” .

In the Zero Tier Central on my browser, the Nodes are always on “last Seen - 1 Minute before”. Is it normal that they’re not always online?

I am a bit confused, and would be grateful for some help, as I have tried for some hours now …

My Zero Tier Web Central: