CM1100 internet speed slowed down after 4 month

[ardavar]

Hello,

My CM1100 modem worked pretty well for a fiew month. I got around 950Mm on 1Gb Xfinity plan.

Some time ago I discovered that the speed slowed down to 350-400Mbps.

According to Comcast, all settings are OK.

The technician was able to get around 1200Mb with his modem using the same cable connections.

There are a few suspicious logs entries I found.

Could that be the root cause of the issue?

2020-08-25, 16:12:16 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=38:94:ed:9c:48:00;CMTS-MAC=00:01:5c:78:c8:5b;CM-QOS=1.1;CM-VER=3.1;
2020-08-25, 16:12:10 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=38:94:ed:9c:48:00;CMTS-MAC=00:01:5c:78:c8:5b;CM-QOS=1.1;CM-VER=3.1;
Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=38:94:ed:9c:48:00;CMTS-MAC=00:01:5c:78:c8:5b;CM-QOS=1.1;CM-VER=3.1;
Time Not Established Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=38:94:ed:9c:48:00;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

[plemans]

What router do you have connected? 

What speeds do YOU get directly connected to the modem?

And what device are you testing on and what website are you testing on? 

Do you have a screen snip of the cable connections page? its used with the logs to check the signal.