Unplug your router for 30 seconds, it usually work's for me.

Or you could try these method's.

Turn off 'Instant On' and enable 'Energy Saver'
By disabling 'Instant On' and enabling 'Energy Saver' your console will reboot every time you power on, and will therefore renew its UPnP leases. Unfortunately this also means dealing with much longer start up times.

Hard Reset Method
To hard reset your Xbox One, press and hold the power button.

Once rebooted, go back to network settings and re-test your multiplayer connection.

Hopefully your UPnP leases have been renewed and your NAT type now says 'Open' or at least 'Moderate'.