I'd be interested in knowing how QUIC deals with networks where an upstream link has a lower MTU than the LAN, and some intermediate routers are blocking ICMP.
With TCP, the router would be set up to clamp TCP MSS, but how's this going to work with a UDP-based transport?
Both peers will start with a minimum MTU that is deemed to be safe (around 1200 bytes) and will independently start a path MTU discovery workflow from there. That allows each side to increase the MTU without having a dependency on the other end. For path MTU discovery, peers can send PING frames in higher MTU datagrams and detect their loss (miss of their acknowledgement)
With TCP, the router would be set up to clamp TCP MSS, but how's this going to work with a UDP-based transport?