Unstable Connection With really fast Internet Connection

We’ve just moved to a new location and upgraded our internet to a much faster connection — 800Mbps download / 40Mbps upload (previously 100Mbps / 20Mbps).

* At our previous location, Zoom ran perfectly on the slower connection — no issues at all with video, audio, or screen sharing.
* Now, with much faster internet, we’re suddenly experiencing constant “unstable network” errors on Zoom.

We’re running daily Zoom sessions with shared video and sound, and the connection keeps dropping, lagging, or freezing — seriously disrupting our work.

* No issues with any other platforms or general internet use — only Zoom is affected.
* We've tried all the usual fixes: restarting modems/routers, switching between wired and Wi-Fi, testing different devices — nothing works.

This issue is critical for us and needs to be solved immediately.

Has anyone experienced something like this? Any advice or insight would be hugely appreciated.