I would get occasional loss of wireless signal and I just set all my IP's as static on my devices (thanks to FurryNutz).
It's not hard to do. Just go to Basic>Network Settings>Number of Dynamic DHCP Clients (at the bottom of the page).
And then RESERVE them (remember to click 'save'). You can somewhat choose which IP address each has by the order in which you reserve them.
XBOX's don't give a name for their IP like your computer will, so turn each XBOX on one at a time so you'll know which is which.
I tried to do a screen shot of mine but I can't figure that out.

Edit to add: I just re-read your post about the chat rooms. I also have certain friends that I can play with and some I can't if I'm not the host. It's like my setup doesn't work with theirs. So, it may not be anything you can help.
Your settings look good, btw. Those settings are what Furry told me to do.