Ok, free tech support I guess. It could be shitty DNS provisioning, that's pretty common. But are you using wireless? Are you familiar with Buffer Bloat generally, let alone some of the other implicit shenanigans in "traffic shaping"?

A few years ago the cognitive dissonance of people saying "DoH is faster" to the same DNS server(s) started really bugging me: is it really DoH, or is it simply TCP vs UDP? So I wrote a little thing I can install on my laptop to do DNS forwarding over plain old TCP (originally no encryption): https://github.com/m3047/tcp_only_forwarder

Golly, on my wifi TCP was certainly more reliable than UDP. It's due to how wifi devices prioritize and buffer traffic. Maybe they should implement / enable DoH on their own servers.

On the other hand if all of your access from the workplace network to web resources is proxied (and since DoH is a web service), they may not care.