TBH, I'm having the same issue.
Not that it breaks my internetconnection alltogether, but I repeatedly get the "losing connection" warning, I always assumed it's because I'm using WLAN, or because there are usually 4 people using the same connection I do...
Thinking about it now tho, it's not always been that way, and happens to me even on servers with pings below 70, which I never had a problem with in older versions. Aside of that, I don't have that kind of problem with other games like Tribes or TF2.
Not sure if that means it's caused by MWLL, but maybe worth looking into anyway.