I did save settings on upgrade.
I will factory default now and start fresh and see how that goes. thanks for responding. Definitely haven’t installed gcc compiler.
My theory is that it was something to do with DNS rebinding. I setup pi-hole on a vm last week and was using that for DNS for the network, and was getting very many dns rebinding errors in the log. I was still getting the error messages even though I turned off DNS Rebinding Attack Protection.
prior to that I had no issues.
This is my production network (home) so wasn’t doing anything ‘strange’ to the router.
John