You always need a server
that using encrypted chat apps that rely on central servers “puts your fate in someone else's hands
For mobiles on v4 you have to deal with CGNAT and for v6 (if you are lucky to have it) there is a stateful firewall). In addition to that you have the problems of registration, "where am I", offline forwarding, etc.
That, however does not influence the fact that actual messages cannot be cracked. I suspect that Snowden's opinion on the matter still stands - the e2e aspect was not cracked. It is implemented on the phones with the server providing relay and NAT traversal.
The most likely thing to get the miscreants on the police record was the use of encrypted one-to-many channels. Same as in Turkish coup and many other cases recently. Those are usually implemented on the server (though they do not need to be) and can be intercepted.
Biting the hand that feeds IT
