Comment 49 for bug 584529

This has nothing to do with the wifi router.
I see the exact same issue when I use a USB mobile broadband modem instead.
(whops, I thought I had already mentioned that, I hadn't).

Also note (again) my steps to reproduce the issue:

 Steps to reproduce:

 Make sure you're not connected to network
 Open Thunderbird
 Connect to network.
 CHECK THAT THE NETWORK CONNECTION WORKS BY OPENING A WEB PAGE IN A BROWSER
 Go to Thunderbird and click "get mail"

So, between connecting to the network and having TB check mail, I check that everything else works by surfing the web with a browser. No matter how much time I wait, the FIRST time TB tries to fetch mail it systematically fails, even if it is several minutes after connecting to network; the SECOND time it succeeds.

Frankly, I wouldn't look for the cause of this outside TB.

By the way, my DNS is NOT defined as 192.168.1.1, it is 8.8.4.4 (Google's DNS).

Regarding the other issue, the NONSENSE is that:
1. when connection to the server fails for whatever reason, no matter whether it is because the host is unreachable or because the name can't be resolved, it must show a message telling you what the failure is (such as "couldn't resolve domain name", or whatever), not a message that tells you what was the last thing it did and which doesn't even tell you whether it was a success or failure! ("looked up xxxx", as in "I looked up the domain. Don't ask me whether I found it or not"). When you tell a program to do something it must end in either or two ways: (a) "I'm finished doing what you asked me: the result is xxxx", or (b) "I couldn't complete the task because something went wrong: the error was xxxxx".
2. Even if you are not connected to the internet at all, it still says "looked up gmail.com"!!!! That's complete nonsense.