reply to Rob37
1st put WAP@2nd room (no WAN) use stumbler to verify less noise Assume you test ensuring: just one client exists using the network, using WPA2-AES with strong passphrase, with 2.4GHz SSID unique from the 5GHz SSID. Also unplug your frig, cordless phones, etc. to check for effect too.
Better *Stumbler's will graph both signal strength AND noise level, and also WITHOUT connecting/authenticating to those networks. Do you then observe actual high noise level on all 2.4GHz channels (versus at a friend's house or public hotspot)?
Does it vary with time of day? Do your neighbors report similar issues? Can you arrange with them, to let you graph noise level from your laptop/stumbler within/around/near their premises?
Before/without paying to move a connection to another of your rooms: If you have extra 2.4GHz WAP to try in another room, you should be able to partially set it up there (WAN left Unconnected). So the radio is ON enough for your laptop/stumbler to graph the signal strength AND noise level for comparison before paying anything.
i.e. other room WAP/SSID won't be functional yet for speed-test or internet access, but radio will be on, and functional for stumbler measurement of signal strength AND noise level. (Or so I believe, can't say I've done this myself).