I am on a MacBook Air running OSX 10.10.2. I try to connect to an HTTPS website on Firefox and I get the message
Your connection is not secure
The owner of www.google.co.il has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.
This site uses HTTP Strict Transport Security (HSTS) to specify that Firefox may only connect to it securely. As a result, it is not possible to add an exception for this certificate.
When I click on advanced I see
www.google.co.il uses an invalid security certificate. The certificate is not trusted because the issuer certificate is unknown. The server might not be sending the appropriate intermediate certificates. An additional root certificate may need to be imported. Error code: SEC_ERROR_UNKNOWN_ISSUER
When I try to open a non-HTTPS website it seems to work and when I connect to a WiFi with a password it everything works. I have tried clearing browser caches and clearing history, turning off and back on again and using chrome.
I used Safari and I was able to bypass the error but then it tells me "העמוד אליו הגעת חסום לגלישה!" which means "The page you reached is blocked for browsing!" but it doesn't say why.
I don't have access to the router but everyone else whose computer is connected to this WiFi seems to work just fine.