Ranked Matchmaking busted? (Steam, PC)

I haven’t been able to join a ranked game in the last 5 days, it cycles through
Comparing Skill rating- expanding player pool- dissolving lobby - identifying potential players- wash rinse repeat .
I haven’t seen this issue come up in any reviews or such on Steam and their fixes says they’ve greatly reduced match making times. Does anyone know what is causing it?

Your ISP, blocked NAT and probably your router.

Full ranked lobbies in seconds.