I've blocked UDP in every edge network I've operated since the late 1980s because it could be used to facilitate firewall bypass in the style of quic. I might not be alone. Quic is something I'll expect my ALG to use, because it's a great thing.
I suspect the user mode networking aspect may also be puzzling. When Linux and BSD and Windows and mach all have it in the kernel as just another address family, more apps will understand how to use it. I know that's not the plan but the plan may have to evolve. p vixie
