If you are getting Reliable Channel Overflow messages this suggests one of the following issues:
Your internet connection or the server's internet connection is having problems.
Your connection is overloaded, for example running a peer-to-peer filesharing application in the background.
There are other computers on your local network using your internet connection.
The server you are on has its network connection overloaded.
You are running on a wireless connection with a poor or inconsistent signal.
You have a Virus or Trojan or Internet Worm infection that is generating traffic.
You are connected to the internet using a dial-up or other low-speed connection.
You have your rate or cl_updaterate or cl_cmdrate settings too fast for your internet connection.
You can help to identify and eliminate the source of your problem by:
Shut down all unnecessary programs on your computer before playing.
Disconnect all other computers in your household to see if they are causing the problem.
Scan all computers on your home network for virus/trojan and spyware.
If you are running on a wireless network, try connecting using a direct ethernet cable and see if the problem goes away. You will probably have to disable the "Wireless Zero" service while you are playing as well.
Follow recommended tuneup procedures for your 56K modem connection (but expect this error to happen from time to time with dial-up modems). Dr Tweak's Advanced 56k help guide
Safe rates for dial-up connections are typically around 3500-5000, while broadband connections should be able to safely run 30000 or better. You set this in your game console (~ typically) by entering: rate <value>
The default cl_updaterate is 20, setting the value to a higher number increases the download demand on your connection. Set this in your console: cl_updaterate 20
The default cl_cmdrate is 30, setting the cale to a higher number increases the upload demoand on your internet connection. Set this in your console: cl_cmdrate 30
https://support.steampowered.com/kb_arti...-FVCM-1111