Situation: My friend has been trying to get a new router since their previous one was a rental from their ISP.
The previously perfectly acceptable download speeds (10-20 mbps) became abysmal download speeds (<5 mbps).
But the ping time and upload speeds remained in their normal ranges for the same speedtest.net servers.
Things that were changed:
Nothing but the router and modem were changed on the day of the swap.
Yet when we put back the rental router, it experienced the same abysmal download speeds.
The wired connection to any of the routers we have tried remains perfectly fine.
The modem was changed, but the fact remains that the wired connection works fine.
Things we have tried:
Multiple routers: Two Linksys routers, a netgear, an ASUS, and we're about to try a TP-Link one
Setting the routers to various combinations of g only, b/g, n only, auto, etc.
Replacing one of the ASUS's antennas with a high gain TP-Link antenna
and countless other possible solutions or troubleshooting steps.
We have tested the connection on various combinations of tablets, phones, laptops, and desktops, both wired and wireless in various parts of the home, but still have not come to a conclusion as to the source of the problem or a possible solution.
They're not even operating at G speeds - most of the time they were operating around 0.1-0.3 mbps.
I used one of their older Linksys routers as the primary access point, and an ASUS router as a repeater to circumvent the concrete garage, and that boosted all devices but one to normal speeds.
The remaining device is a custom build with a Linksys AE2500 USB Wi-Fi dongle. It works in all locations in the home except in his room (where it gets decent ping, craptastic sub-1 mbps download, but normal 6-7 mbps upload).
We have tested other devices in the same room, and they have acceptable ping/download/upload speeds, so it may have something to do with that specific adapter and the wall. We will be going back to Micro Center to grab a different adapter, any suggestions? (brand/model, USB or PCI, etc).
Edit - Yes, we were using inSSIDer as well. One thing we got from that was that the TP-Link 8dBi high-gain antenna does absolutely nothing.
Yes I use them myself for a couple of difficult spots in the home and have put them in many client homes. They are fast enough for anything other than streaming full blu-ray images from an NAS full of iso images.
If you have interference issues from devices with motors, just put the fan or whatever either on another outlet or place a 6 ft. extension cord on it -- that works as well as expensive suppressors.