I wrote:
Next time it fails I'll try that. My guess would be that the connection will timeout even though an established connection to the same server will continue just fine, but I'm not 100% sure I've actually tried it to be sure.
OK, conveniently enough it just failed on me.
Yes, I can still establish a new SSH connection to my server. I cannot, however, establish a web connection to a page on the same server.
Now, a few minutes later, the connection seems to have died altogether. SSH dropped, VPN dropped, etc. Router still thinks it has a good connection, but I can't get anything out of it now. Time for a router reboot methinks...
Hmm, restart left my router IP-less. Swapped to bt_test login, that worked, back to my own and that's also now worked but connection still "dead" (no SSH even) but pinging my server is fine (1472bytes packets, 1473 packets intermittent). Ah, several minutes later it's back.
I'm going to create some test pages on my web server of varying sizes to see if they work when the link seems dead.