Not sure if this will help some people but a while back I did some research around my Internet connection. I was mainly after how to ensure I didn't get drop outs. My problem was a little bit different in that I was getting disconnected from the Internet where as I think a lot of people here have been kicked from the game but are still connected to the Internet.
Anyway the more you know the more you might be able to improve things.
My connection is ADSL so most of the info relates to that. Others on here probably know more than me and I encourage them to post. Especially if you have links to good articles about other connections such as cable or fibre.
Common Problems with your ADSL
Increase Broadband Speed Guide
Speed up broadband: five top tips
ADSL line sync and modem choice
Repetitive Electrical Impulse Noise (REIN)
The last link is ADSL related but could be used for any wired network connection.
I am by no means an expert and networks and Internet connections are complex and messy. I will try and help you if I can but the forums I have posted links to are probably a better place to ask questions.
Be careful with trying to do some of these ideas as a little knowledge can be dangerous, so if in doubt get a qualified technician to have a look at your cabling. Safety first.
I have had my home network setup for about 6 months now and have had very few if any drop outs due to me playing online. I usually play with people on the other side of the world from where I am and it is rare for me to get lag.
Hope this helps some people.