Same issue here in Germany/Munich/Telekom ISP - looking at traceroute, I assume there is an issue with Deutsche Telekom’s WAN routers; seeing many timeouts after d-ed5-i.D.DE.NET.DTAG.DE. I have been unable to log in to Zwift since 6 PM CEST yesterday.
I’ve just switched my Zwift machine to a VPN service provider and routing via Switzerland works like a charm and lightning-fast.
BR, Thilo