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Forum Discussion
dolphinsarecool
Apr 24, 2025Aspirant
Netgear CM1200 and Xfinity losing upload speeds randomly
I recently upgraded my service with Xfinity. I was previously on their 400down/35up plan and upgraded to the 1100down/35up plan. Everything worked great for the first week and then the second week I ...
plemans
Apr 24, 2025Guru - Experienced User
The CM1200 tends to be pretty solid. And xfinity has been pushing out the upgraded firmware to some.
Your best bet would be to check the cable connections page when its connected and the event logs. That lets us check the line connection
- dolphinsarecoolApr 25, 2025Aspirant
Okay, cool I can pull those up when I get a chance. So, while I was troubleshooting the modem, I hooked up my older modem I used for years which was the cm500. Would the cm500 be able to handle those speeds as well? I am pretty sure it can too. But I was having the same issue on that modem with the stable and steady download speeds but dropped to 1mbps upload.
The xfinity technician assured me that both the modems were either bad or couldn't handle the upload speeds. And I didn't really believe that.
- FURRYe38Apr 25, 2025Guru - Experienced User
Will need to see cable modems connections data page and event log pages please.
The CM1200 can support up to 1Gb only.
I believe the CM500 was never rated for 1Gb. I had a CM700 series once and it wasn't fully rated at 1Gb thought ISP said sometimes it could but didn't officially support it.
If your seeing slow downs regardless of either modem, there is a ISP line issue. Cable Connections page will help in that some.
- dolphinsarecoolApr 25, 2025Aspirant
I'm only having issues with upload speeds, not download.