All PCs wireless connectivity suddenly fluctuating

All of a sudden, all three of my laptops' wireless network speeds and signal strengths are fluctuating. The speed used to stay at a constant 54 Mbps and the signal strength was always excellent. Now randomly the speed drops to 48/18/11/5.5 while the signal strength is still excellent, or the signal strength goes to very good/good/poor while the speed is still 54. One of my laptops, the Dell Latitude x300, disconnected completely quite often, the IBM Thinkpad T40 would rarely, and I think the Dell Inspiron B130 wouldn't actually disconnect at all, though it may have once or twice, I don't recall. Pinging google.com or Charter Spectrum's DNS on the Latitude occasionally got timeouts, while the other two wouldn't at all, although the thinkpad did a few times. When the speed or signal is down (sometimes they both go down at once but usually not) they would all ping just fine. I couldn't ever catch when the latitude timed out whether or not the network dropped, at some points the SSID would disappear and the signal bars would be empty for a split second, and I think it would timeout then but I don't think that happened every single time it timed out.

I still have the AT&T modem/router combo from when I had DSLExtreme, and so I plugged that in and turned off the Charter wifi, and tried connecting the AT&T combo to the Charter router to use for wifi. I wasn't able to disable DHCP on the AT&T combo so I just set it to an IP range the Charter router didn't use, I'm pretty sure it worked, I was able to connect to the AT&T combo's wifi and go to webpages. But all my laptops still said the same thing they were with the Charter router, signals dropping, speed dropping, timeouts. I disconnected the AT&T combo from the Charter router and factory reset it, then tried connecting to its wifi again, and it still does the same thing, speed dropping, signal strength dropping. I just got the combo out about a month ago just to mess with it and it was constantly 54 Mbps and excellent signal strength the whole time as far as I know, but of course I wasn't paying all that much attention to it.

Nothing has moved, the inspiron is sitting right next to both routers, the other two laptops are in the next room with only part of a wall between them (it's a big open entryway), I even tried placing one of those laptops right by the router as well, it made hardly any difference.
It's all where it has been for 8+ years with no problem, besides for different routers/modems being in the router/modem spot. I switched to Charter about a month ago and this started about a week ago.

The only thing I can think of is that there's interference on the wifi, because nothing else has changed, anything and everything wired works just fine and it's two routers and happens even without the modem connected to it, so it can't be the modem and it can't be a buggy router. The thing is, I checked other wifi's in the area and there aren't many, it's a small town, and they all seem pretty weak. I checked earlier today and there was a maximum of two on one channel, if I remember correctly, I believe it was channel 1. The Charter router was on channel 1, and the AT&T one had always been on 6, and when I first got the Charter one I think it was on 6 as well. So I switched the channel to 6, and it's hard to tell, but I think it might possibly be slightly better, I think they might not be completely disconnecting as much, but they're all still doing the lower speed/signal thing. I just checked the wifis again now, and it looks like there's one other wifi network on 6, one on 8, two on 11 and two on 1. The other one on 6 is the strongest of them all, it's about half as strong as my own while the others are hardly there. The weird thing is, switching mine to 1 or 11 didn't make a noticeable difference, and I'm not sure that 6 has either, but it may have made it slightly better. Either way it's still going on. Xirrus Wi-Fi Inspector is what I'm using to see other networks, and 3 or so keep disappearing and coming back, it only steadily detects 3 other ones excluding mine, one on 6, one on 8, and one on 11.

I would chalk it up to just stuff being weird, as long as my internet seems to work fine and get the same speeds. But the latitude would disconnect so much that it was hardly useable, but it seems better now. Webpages occasionally say that the server timed out. Pinging google.com continuously on a wired connection for over 1000 pings gets absolutely no timeouts on the Inspiron, but doing the same thing on the wifi on the Inspiron, which is right by the router, gets at least one or two timeouts. Is that normal for wifi? Doing that on the latitude gets quite a bunch of timeouts, which I think if I was going to a webpage at the time it probably would've failed to connect, and the thinkpad is in between the two. Speedtests have never been reliable since I switched to Charter, so I can't tell much by them but it doesn't seem to be worse than usual.

 

If you want to test with the AT&T router, ensure that you disable the wifi on the Charter router. The devices are likely not connecting to the AT&T router.

Also, if you think there is actually an issue with the Charter router, you can simply take it up to your local office and exchange it. They will ask why, but assuming they have hardware on hand, they will provide you another unit.

 

I did disable the wifi on the Charter router, and ensured that all devices were properly connected to the AT&T one.

Since all PCs acted the same way with the AT&T router, doesn't that show that it's not something wrong with the router? It seems unlikely that both would go bad at the same time when one wasn't even in use, but I guess it's possible. I'm probably going to switch to Earthlink, so I guess then we'll see.

 

I didn't read that it was disabled, so if I missed it, then I'm sorry.

In any case, yes, if the issue persists with both routers, then it's likely an interference issue, or as the issue seems to be different with different devices, it could be issues with those devices.

Are any other devices, such as your phone, also having issues?

 

It was a long wall of text, no worries!

I don't have an internet connected phone, however I do have a wireless printer and a Roku, and the printer is refusing to print unless I turn it off and back on, sometimes turning off its wifi connection (it has a button right on it for that) and turning it back on makes it work, but sometimes it just doesn't unless I turn it off and back on, but I just got this printer and I'm pretty sure it did that from the start, before the laptops started acting this way, but I guess it could have something to do with it. My previous Roku constantly rebooted and I had to get another one a little before I noticed the laptops acting this way, but the new one seems to work fine.

I'll try more wifi channels and see if that does anything, then post back here.