(adsbygoogle = window.adsbygoogle || []).push({}); To force host without packet injection, you need to get a new lobby and change your nat type to strict before it migrates host. This is easiest if you're in a party as it usually puts you in a new lobby straight away. If the lobby merges, back out and try again until you are in a new room. To change your nat type to strict, you have to go on your routers web interface and delete the port forwarding or disable upnp.

Yes, it works every time for me. It might not work for every router, i am using a netgear DG834GT.

I have the same router, but when I turn off the UPnP and click apply wouldn't the internet be turned off for a minute then on again by itself ?
and why not turn the UPnP before entering the lobby ?
the host migration is not the biggest problem to me, the "trying to merge lobbies together" is the main problem.

UPNP basically allows the console to talk to the router and tell it what ports it needs open. And DMZ basically means you are outside of the routers firewall and all ports are open, no need to port-forward. Really UPNP shouldn't effect a device in the DMZ. UPNP is only needed if you haven't set a static ip and put your console in DMZ.

I don't use upnp so im not sure, I just delete the port forwarding on the firewall rules and the router doesn't restart. I use the preset 'All' port forward which does the same job as a dmz, I only have to click one button to do it. I checked that it worked by going to the main menu and back on multiplayer, it went from open to strict. If you have it on strict to begin with i don't think it can find a new lobby. If you get a full party together the chances of it merging lobbies are reduced.

why wud putting it on strict help you get host