I had a problem a little bit like that once, where the wireless part of my router stopped working and the only way I could access the Web was to plug in a cable between the router and my laptop. It worked for everything except the BBC news website and the Thunderbird email client. Some techie friends agreed it was a weird problem and suggested I tried some interventions that I couldn't understand. Then after a good few hours the problem went away all by itself. My techie friends said that they thought the router might have been upgrading its firmware. I still don't understand to this day how such a problem could have happened.
I did manage to get access to the BBC news back before normal service was resumed, by searching for "BBC news UK" and clicking on one of the hits, which got me there, though the URL was a very long one I'd never seen before. My usual bookmarked URL was useless till the problem fixed itself.