cm1000 issues

[plemans]

What issue are you having?

More details are going to help.

You didn't get all the channels in your post but the ones you did, look pretty good. 

[AverageJoe88]

i have xfinity gig speeds but i’m not getting what i’m paying for. i’ll run a test and get somewhere around 800+ download. then i’ll run another speed test and it will drop into the 500. upload test will spike up to 40mbps then it’ll drop down into the 10’s and slowly crawl back up to 40. my speed test are inconsistent. i checked the logs on the modem and i’m getting SYNC timing synchronization failure and no ranging response received-t3 timeouts. how do i fix this

[FURRYe38]

Are you speed testing with a wired PC connected directly to the modem or is there a wifi router in the mix?

Please post a copy and paste of the modems connection status page.
Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Be sure to power OFF the modem for 1 minute them back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...

[plemans]

Do you have a screen snip of the cable connections page? 

Also, how are you speedtesting? many sites are unreliable at speeds >500mbps. 

if you have xfinity try speedtest.xfinity.com