So we're opening something like console gaming club and i have 30 xbox360 consoles on my hands.
I need to come up with some kind of billing system based on time limit.

I've tried some solutions:
1. User Manager + DHCP login - seems to work but doesn't disconnect user when his time is up.
2. User Manager + PPPoE server login - works great, disconnects people on time, but seem to have negative effect on Xbox Live connectivity (can't connect to some matches, chats, parties, teams). This looks like UnPnP doesn't work with PPPoE connections. Tried making static PPPoE interfaces for each client - it had no effect at all.
3. Hotspot + MAC login - doesn't kill connection on time
4. Hotspot MAC login to User Manager doesn't seem to work at all.

Any more suggestions? I'm in pretty tough situation here since x360 can only login with PPP or MAC, so please advise.

Bumping with more accurate network chart:

3. Hotspot + MAC login - doesn't kill connection on time

+ script that would remove the active user after the uptime limit is reached

should be easy to do, just a suggestion