I might be overreacting, but I find this phrasing dangerous. It implies that you turn off your Firewall and antivirus programs while being online for all programs and websites. This to me is a dangerous action and I would highly advise against it.
I think an approach worth trying is deleting cookies/history, disk clean up on Windows, command prompt run as administrator and type: ipconfig /flushdns and Enter
like here:
C:\WINDOWS\system32>ipconfig /flushdns
Windows IP Configuration
Successfully flushed the DNS Resolver Cache.
C:\WINDOWS\system32>
Why should we disable those things which are there to protect us online when it’s clearly an issue at their end? Haven’t seen it in a while though but when it happened all other websites I visited worked absolutely fine. So it’s clearly not on my end. And in my case it cannot be a virusscanner because I only switch that on once a week to scan.