1c. Always in alterIWnet.ini, make sure that "Webhost" is set to "auto"
remember: after that, open Task Manager, click File, than Run and type ipconfig /flushdns
2. go to your players folder in;
C:\Program Files\Activision\Modern Warfare 2\players
and delete these files:
config_mp.cfg
settings_c.zip.iw4
settings_m.zip.iw4
3. probably, if it doesn't still work you have been banned.
If you are a cheater, don't even try asking a aIW member to be unbanned.
If you aren't a cheater, maybe you have the same XUID of a cheater, or a similar nickname, or the same IP (quite impossible, but maybe you have been in the same Internet Cafe where was a cheater).
So go to aIW chat and send a PM to one of the people in the list who have the aIW tag, or ask in the main chat.
Follow aIW instructions and your error will disappear.
Another suggestion by Insignia:
try resetting your router and re-apply your settings
remember: after that, open Task Manager, click File, than Run and type ipconfig /flushdns
adamhenry suggested another thing to do, but it's a long post, so i don't incorporate it here.
Link: viewtopic.php?f=30&t=3239&start=10#p32388
UPDATE: this seems to work
alterIWnet • View topic - [Guide]Connecting to IWNet... error
Suggestion by Neriol De Ville:
Hey, I had connection problem for 3 days, but i solved it today... by ENABLING my LAN network which doesn't actually exist... but this got rid of my connection problem, so try playing with your networks enabled, it might help, it helped me =)
remember: after that, open Task Manager, click File, than Run and type ipconfig /flushdns
Suggestion by fr0stie2:
Goto: Control panel => network and internet => Network and sharing center => then click local are connection =>Properties => click the tab sharing =>and make sure the first checkbox is NOT checked!
Here is a youtube vid with another suggestion:
YouTube - Call of duty Modern Warfare 2; Connecting to IWnet.... Solution! Fix!