The "weak ephemeral Diffie-Hellman key" error indicates that the server is trying to use an obsolete encryption cipher which is vulnerable to the Logjam attack that was in the news earlier this year. ''What does that mean?'' Even though you trust the server, a "Logjam" attack compromises the security of ''your individual connection'' to the server, lowering the protection normally provided by SSL to a level that is easily cracked and read by others on the network. That is why Firefox protects you from making this connection. ''What can you do now?'' The very best solution is to update the server. Please request that for everyone's protection! However, I suspect that is beyond your control and might not happen soon. As a workaround, you can try disabling these old ciphers ''in your Firefox,'' which hopefully will force the server to try some more secure ciphers when connecting with you. Here's how: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter. Click the button promising to be careful. (2) In the search box above the list, type or paste '''dhe''' and pause while the list is filtered (3) Double-click the '''security.ssl3.dhe_rsa_aes_128_sha''' preference to switch it from true to false (disable Firefox from using this cipher) (4) Double-click the '''security.ssl3.dhe_rsa_aes_256_sha''' preference to switch it from true to false (disable Firefox from using this cipher) Then try the server again; you might have to reload the page using Ctrl+Shift+r to bypass cached information. Success?