I routinely disable IPv6 on Windows OS and on MacOS. I manually set DNS server numbers - instead of trying to rely upon DHCP.
Otherwise, you might try some of the suggestions:
'Incorrect warning: Your connection to this site is not secure - #8 by 289wk
‘Incorrect warning: Your connection to this site is not secure - #10 by 289wk’
And . . . you might get some clearing Site Details ideas from:
‘Gmail refreshing non-stop and trouble logging in - #2 by 289wk’