Cannot access HA using Nabu casa Link if connected to the same home network


When I try to connect to home assistant via Nabu casa link with my desktop computer or my laptop computer (which are connected to the same wifi network as the host running home assistant), using Chrome, Edge or Chromium, I get the error “Unable to connect to home assistant”. Refreshing the page a lot of time will eventually success, but if I refresh the page again I get the same error.

On the same computers, firefox works without issues. I can also reach HA without issue using the internal ip address:8123. The companion app on my android phone also have no issues.

If I connect the computers to a cellular network using my smartphone hotspot, everything works with every browser.

What could be the issue?