..reads platform specific, Piet. Can happen without warning, witnessed several years ago on MS zealous use of "security protection" and inability to narrow down the exact reason. Shotgun technique applied, swap to alternate MS platform version. Slow or nil internet access cured. Just wasted days and days trying to locate the reason for the corrupted WWW access all of a sudden.
Hardware is cheap these days, am a Linux Ubuntu ( was Redhat ) instructor one time, all i use. Though i keep a spare ex gov. Dell Optiplex 9020 with Win10 on it to support apple ipad repairs i do at times. All the working machines here are DEll 9020's with 256G SSD i-7 procc installed and Ubuntu installed. For a few hundred dollars each i have 4 workstations and a never repeated HP laptop, erratic problems with HP, a brand i do not purchase at all these days. Not sure it helps though i would change platform version Piet to save the sanity, usually in company with new or more recent hardware upgrade alas.
FWIW i have 7 apple ipads here, you can use them to do quick checks on items such as this forum. When main workstation seems to be not working. Use ipads for stage work, hence the 7 or more in stock here. HTH j.