For a while now, I have been having issues with several websites, which tell me either just after logging in, or after one or two clicks, that my session has expired and I need to log in again.
Problem history: At first I thought it was the website's fault. After it occurred on several unrelated websites, I thought it was Chrome's fault as for at least some of these websites, the problem did not occur when using Firefox. Then later I found a website where also Firefox (or Microsoft Edge) didn't work, and I thought it had to do specifically with that website. But now I have encountered the same issue, for all my browsers, on at least two unrelated websites (namely https://www.sbb.ch and https://www.digid.nl).
Can anyone tell me what is causing these issues? And how do I prevent this, so that I can actually use these websites again?
What I have tried: So far I have tried removing cookies for these websites in different browsers, but the problem remains. I am also positive that my name/password combination is correct on both. If I use a different combination, it specifically tells me the combination is incorrect. As mentioned, I have tried these websites using Chrome, Firefox and Microsoft Edge, all while using Windows 10. I do not have any specific additional firewalls installed as far as I know. I'm usually accessing the internet via a semi-public WiFi network (password-protected) hosted by the apartment complex I'm living in, if that's relevant.
Edit: To add to the above: the same websites do work properly when accessing them from work (with a different machine, on a different network). So either the problem is related to my machine, or to the network used to access these sites.