CM1100 internet speed slowed down after 4 month

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;