Download speed suddenly very slow on ALL devices, upload speed normal

[PolySci]

All of a sudden today my download speed has dropped from the usual 100Mbps to 2-3Mbps at best. I believe it's a problem on my ISPs side (Comcast) but just wanted to ask for any suggestions because if I call Comcast and tell them to come fix this it's going to takes weeks. I have a Netgear Nighthawk ac1900 router and a Comcast provided modem. I've tried 3 PCs - my desktop (usually gets 90-100Mbps over wifi) is at 2Mbps, my laptop (usually get's 50-60Mbps over wifi) is also at 2Mbps. Finally I used an older laptop (normally gets 20-30Mbps over Wifi) to wired connect to the router and then the modem - both also said 2Mbps. The upload speed is showing up as totally normal on every device - somewhere between 9 and 12Mbps. On top of this, if I use the Comcast speed test instead of the Ookla speed test or any other test, it still says on each respective device that I'm getting the speed I'd normally expect from that particular device, which is a bit of a piss take when I'm very clearly not getting that based on my browsing experience at the moment - just seems pretty convenient for them. Is it possible this is a problem with my Modem? Could it even be something past the Modem with my router or devices (seems very unlikely)? Could it be a problem with the cable in the house? Any advice appreciated.

 

[digitaldoc]

You need to plug a computer directly into the modem, thereby bypassing the router, and rerun the Speedtest. If the speeds are normal, than the issue is the router.

I suspect the issue will persist. The problem can be with the modem, or the wiring.

Be sure to reboot the modem.

This exact situation happened to me last twice in the past. Both times it turned out to be the splitter outside the house. One time the splitter needed to be replaced, and the other time the splitter was wired wrong (by the cable tech no less) and the run to the cable modem was on the wrong limb of the splitter (it should be on the one with the strongest signal, designated by the least negative of the numbers).

 

[PolySci]

You need to plug a computer directly into the modem, thereby bypassing the router, and rerun the Speedtest. If the speeds are normal, than the issue is the router.

I suspect the issue will persist. The problem can be with the modem, or the wiring.

Be sure to reboot the modem.

This exact situation happened to me last twice in the past. Both times it turned out to be the splitter outside the house. One time the splitter needed to be replaced, and the other time the splitter was wired wrong (by the cable tech no less) and the run to the cable modem was on the wrong limb of the splitter (it should be on the one with the strongest signal, designated by the least negative of the numbers).

Plugging directly into the modem was one of the first things I tried as well as rebooting it. Unfortunately, this also shows the same very slow speed. It could well be the modem, I just wouldn't expect the modem to cause a massive speed drop (literally 50 times slower) - I'd think it'd just give out. Thanks for the input all the same, but this is hardly good news for me as it means I'll be waiting weeks to see a fix for this unless I can do it myself.

 

[digitaldoc]

Did you take a look at the splitter?