Just to add to this thread - also experience the same problem since upgrading to BigSur in the last month. No issues before upgrade. Have to reboot several times a day to resolve. Network connectivity completely drops out through both wired and wireless. Problem does appear to be DNS - browser cannot resolve hostnames. I have noticed that often the problem is triggered when I start Docker Desktop, however I have had it intermittently fail at other times (presumably when some other service starts that I haven't been able to identity?)

Just to add to this thread - also experience the same problem since upgrading to BigSur in the last month. No issues before upgrade. Have to reboot several times a day to resolve. Network connectivity completely drops out through both wired and wireless. Problem does appear to be DNS - browser cannot resolve hostnames. I have noticed that often the problem is triggered when I start Docker Desktop, however I have had it intermittently fail at other times (presumably when some other service starts that I haven't been able to identity?)