UPnP issue after changing to new modem

After you set up the new router and enabled Upnp did you power down then modem and router to power-cycle them, this usually helps devices recognize new settings or harware properly.

Hi Rockslide FPS! It looks like the new modem does have a router built in. It has 4 ports on it, correct? If so, you won't need the Linksys router anymore. You should try plugging the Xbox into the Modem directly. Here are instructions from Arris' support
site on how to enable UPnP for the new modem/router.
moto.force.com/.../TG862G-NA-UPnP-Setup

Again, I'd eliminate the old Linksys router and plug into the new modem/router directly. Then I would make sure the UPnP is enabled on the new modem/router. Try that and then post results. I am a network engineer by trade.

So i had this issue when i was trying to change my NAT from Strict to Open. What worked for me was turning on UPNP on my modem/router. I just did a simple google search "How to enable UPNP on (modem/router)". Once I turned that on it has kept my NAT open
permanently. Good luck and I hope this helps.

I hope I can help. When I had this issue I had to enable the UPNP on my wireless modem. Solved my issue when I made this change. Hope you get it taken care of! Good Luck!

Turn on UPNP on the router. Then take out any port forwarding or DMZ. It won't work if those are turned on. You also might need to clear your NAT table in the router . There is a good tutorial in the NAT section on xbox.com.

support.xbox.com/.../nat-error-solution

I didn't reset my cable modem, just the router. After doing this both my 360 and One have open NAT.

"Turn on UPnP to refresh your NAT table

Step 7: Turn on UPnP to refresh your NAT table

UPnP is a standard that helps routers communicate effectively. If your router or gateway supports UPnP, it is likely enabled by default.

In some scenarios, you may be able to resolve connectivity issues by refreshing the Network Address Translation (NAT) table. To refresh the NAT table on a router where UPnP is already enabled, you need to disable UPnP, save your changes, and then power cycle
your router. After that, you will need to turn UPnP back on and save your changes.

Important Do not use a combination of port forwarding, UPnP, and perimeter network (also known as DMZ) settings. If you previously enabled perimeter network functionality on your router, you must disable the perimeter network before you try this procedure.

Follow these steps to turn UPnP off and on:

Log in to your router's web-based configuration page to and make sure UPnP is turned on.

Note Refer to your router's documentation or support website for help turning UPnP on for the first time, or off and then back on.

Note Make sure that the router is restarted each time you update any of the router settings. If the router does not restart automatically, manually restart the router.

Turn the UPnP setting off, and then save your changes.

Restart your console and all your network hardware (your modem and router).

Log in to your router's web-based configuration page to and make sure UPnP is turned off.

Turn the UPnP setting back on, and then save your changes again.

Restart your console and all network hardware (your modem and router)."