"secure connection failed"

“The connection was interrupted
An error occurred during a connection to google.com. PR_END_OF_FILE_ERROR”

I have three browsers on my pinebook pro: chromium, firefox and vivaldi.
Recently when I try to open a web site with chromium or firefox I get the above error, or this one:

“No internet
There is something wrong with the proxy server, or the address is incorrect.
Contacting the system admin
Checking the proxy address

Vivaldi works normally.

What should I look for in order to solve this?

Seems to have fixed itself, both the browsers work now.