Getting slow internet response for browsers other than Safari (MacOS Mojave)
In the event that you threw out something you shouldn't have, first thing to do would be to boot into Recovery and overlay the OS.
The reinstall from Recovery (as opposed to a full wipe & install from Internet Recovery) will ensure all essential OS components are in place without changing any user data.
btw, resetting the NVRAM will do nothing at all for this type of issue.
A quick Google tells me OSStatus error -9806 is errSSLClosedAbort which sounds like an internet security component is not working properly.