After quite some testing I found that my issues using my work laptop at home come from the “auto proxy discovery” setting that is set by my employers profile on my Mac. I can disable it and everything works fine, but it enables it self due to the profile settings. I can reproduce this with other Mac laptops by enabling the auto proxy discovery setting.
It seems to lead to very slow DNS lookups in Safari and other applications, e.g. Office365. Most of the time (99.9%), the requests (e.g. to a website) times out. Sometimes DNS gets resolved after e.g. 50 seconds and then the page is loaded with the expected speed in milliseconds.
Additionally I have the issue only when I am connected via a Wifi. If I am connected via ethernet it works.
I only have the issue since we got the connectbox 3 when we upgraded to fiber. It is really annoying and I have colleagues that live in different cantons with the same problem => so it seems either a general issue with connectbox3 or sunrise network configuration.
I am pretty sure anyone can reproduce the problem: connect via wifi (the native connect box3 or another wifi access point that is using connect box 3 and the sunrise network for internet), enable auto proxy detection in the proxy settings of the wifi and the issues appear (check in safari, Mac OS native services or Office 365, it won’t occur with e.g. chrome, as it ignores this system setting).