I've hosted through my linksys without any problems, both on my lan and through the net. You need to give us more info on the problem you're having:
1. You say the folks get kicked. Do they get a message? What comes through on the console? Do their pings go to 999 before they're kicked?
2. Are you using the default settings on your router? If not, what have you changed?
3. What operating system are you using on the host machine? If it is XP, have you updated your network drivers?
4. What model router do you have? Have you recently changed anything on it? Are you running the most up to date firmware from linksys?
5. Does this happen with machines on your network, or just with machines coming in through your WAN port?
If folks can see the game and are connnecting, I doubt if it is the router unless it is dynamically resetting your machines ip address. I have no idea why it would do that, but it would cause folks to lose their connection to you.
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"If your philosophy does not produce corn, I don't want to hear about it." - Red Bear