ARRIS SURFboard SB6190 Connection Speed Problem

This Xfinity account with a SB6190 modem is receiving significantly reduced interned speeds.  This SB6190 had received  275 Mbps up until about June 2020. Customer continues to receive good upload speeds of 10 Mbps. Xfinity Technical Support believes problem may require SB6190 which will require expensive upgrade to Motorola DOCSIS 3.1 modem . Customer believes problem may be an Xfinity issue supporting SB6190 modems. (For instance, Xfinity could send a bad boot/config file causing lowers connection speeds to SB6190 modems.)

Xfinity customers with SB6190 modems please post following:

1) Xfinty internet service tier.

2) Connection speed test results from https://speedtest.xfinity.com/

3) Advise if SB6190 event log found at http://192.168.100.1/cgi-bin/eventlog contains following error messages ‘TLV-11 - unrecognized OID’ and/or ‘No Ranging Response received - T3 time-out’

4) Post your approximate location.

Here are my SB6190 results:
1) Xfinity 275 Mbps Internet Service

2) Download = 91 Mbps. Upload= 10 Mbps

3) My SB6190 event log does contain error messages ‘TLV-11 - unrecognized OID’ and/or ‘No Ranging Response received - T3 time-out’

4) St. Paul, MN