Bitdefender blocking Edge

Windows 10 64 bit

I noticed a connection attempt from a site dev600.com to my Chrome browser with an unmatched security certificate. I briefly enabled it thinking it was just an oversight by the site owner but then quickly blocked it again when it made no difference. This may or may not be relevant to what's below.

An hour later, I opened Edge but couldnt' connect using it. Chrome works fine but not Edge. I've cleared cookies and cache but still no joy. Diagnostics said it was being blocked by "Security or Firewall settings".

When I go into the Firewall settings on Bitdefender, it shows msedge.exe has been blocked. When I click on View Application Rules, I click the down arrow next to Ms Edge and it shows me maybe 50 different lines, all of them saying Any Network, Any Protocol, Both Traffic, Any Ports, Any IP with the switch toggled blue (for 'on'). The very last line for Edgie isn't switched on. When I try to switch it on, it says that this rule already exists and leaves it switched off.

I've obviously tried several restarts of my pc and rebooted my router to no avail. Any help appreciated, please!?