Particular server I mean; could you name some of the servers you tried?
It's possible that the servers you tried to join are broken, too far away or have other problems.
As for your internet, you can test it here:
414 is waaaay too high.
I get between 23 and 60 ping on European servers and a 100 to 120 on American and Turkish servers. (I am located in Netherlands)
400 ping is likely to just get you auto-removed for having a super unstable connection.
Could you post the image of the ping-test ?
Also if you are using wireless, it sometimes helps to use wired instead.
2 more things.
One is; please edit your posts instead of multi-posting if you wish to add something.
Two, I will be cooking my dinner so I won't reply for a while.
I purchased Mount and Blade:Warband before it was on Steam, and i recently purchased the Napoleonic Wars DLC on the Humble Store, however it only allows me to redeem it on Steam and Steam will not let me activate it because i don't own Warband on Steam. Is there anything at all i can do?
Generally speaking, it's best to buy expansions/DLCs from/for the same platforms, as in the past with many games there have been such issues. (dawn of war comes to mind !)
Perhaps it's best to ask the humble store, and see if they can help you out. Perhaps they can give you the key instead of the steam game, so you can use the key for whatever platform you are using warband with.
Tonight, all of sudden, I started getting an "Incorrect serial number" message when trying to join any NW servers. I entered my CD key manually when asked, to no avail. Then I ran regedit and pasted my CD key back in there, but that didn't solve the problem. Restarting Steam didn't fix it either. Any other ideas?