The NAT firewalls do not like P2P UDP traffic. Majoritoy of the routers lack the smarts to passtrough QUIC correctly, they need to treat it the same as TCP essentially.
NAT is the devil. bring on the IPoc4lypse
QUIC isn’t generally P2P though. Browsers don’t support NAT traversal for it.
NAT is the devil. bring on the IPoc4lypse