I have a ADSL2 connection with 15.6 Mbps download and 0.82 Mbps upload which is typical or on the high end for Australia.

Whenever I join an Australian server (normal ping to exp servers is 90ms) while there's another internet user in my house, for example downloading something or watching Netflix, or if I join a US server (260ms ping) I often lose control of my character - it starts moving in a straight line no matter what I press, or starts flicking around. Alternatively I get stuck in the side of a house after trying to close a door and get hit repeatedly by zombies while flicking between many different locations (inside house, inside nearby shed, outside, running into a fence). I have two friends also with typical Australian internet who have the same experience. We are all able to play other MMO/online FPS games without these problems.