Systematic network protocol error after a few minutes

Hello,

I am connected via Wifi to a BBox, but for some time now, I keep losing the connection and even though Windows tells me I am "connected, secured", Firefox only returns network protocol errors. Nothing loads. I have to restart the box for my computer to connect again. It is not a problem with the box because the other computers do not have this issue, and while mine is throwing a fit, it also refuses to connect to my phone via "tethering" (Windows tells me: connected, no internet access).

When I can connect again, it works for a while but the issue recurs regularly, several times a day. This is absolutely unbearable. I try to access the box settings by going to 192.168.0.1 but every time, "the connection has timed out", so I don’t know what to do.

Thank you very much for your help.

Configuration: Windows / Firefox 65.0