Well - a couple of things to try.
First I would try to reset the router (after restarting the computer, but you already did that).
If that don't help, then try to find out if it is related to all servers and characters, i.e. try out characters on different servers, preferably both on east and west coast servers.
There might be a chance that your internet provider has troubles.
A good way to monitor your connection in game is with the command /netgraph 1 (/netgraph 0) to switch off. Ideally it should be a "green lawn", but if yellow or red spikes show up, that would likely be the problem.
You'll probably get a more enthusiastic response to this kinda question in the Tech Issues & Bugs section.
The tech-heads who lurk there are gonna ask you to run a couple of diagnostics programs and post the results, then dig through and give you suggestions on a fix.
So today at around 6:00 P.M. - 7:00 P.M I was playing the game perfectly fine. No lags or glitches or anything. Then all of a sudden I exit a mission map and a notice pops up saying "Lost Connection to Mapserver". I just ignore it and wait it out thinking that it's just a temporary thing and eventually, I am able to resume playing again. Then, like 3 seconds later, it pops up again, and I rubberband about 5 yards back. Then I start playing again, but only to get mapserved once again 3 seconds later. I restart the game, but the problem persists. Mapserving every 2-3 seconds and horrible lagging and rubberbanding. Then, I restart my computer and then start the game again. But once again, the problem keeps occurring. I can't even play because this mapserving lag is so ridiculous. I can start the game and log into a toon perfectly fine. But once I start playing the actual game, that is when the problem shows. Help? Thanks.