Super SLOW speeds....LESS than 1mbps on 300mbps service

I've been having problems with cox being able to deliver the speeds I'm paying for months now. Called & was told it was my modem; tech on phone could not tell me any specifics. Come to find out, they are reading from a card & has no actual technical skills. Modem was bought for gigablast service, as was the router, but Cox couldn't even provide 500gbs so I cancelled the service. Called & got a tech out; was told the coax from outside the house to inside was the problem. 18 yrs out there so it seemed believable. Replaced it w/a single piece screwed directly into the modem. Same problem. Replaced the router & modem w/known good ones for a month. Same problem. Tech supervisor came out & replaced the cable from the junction box to my house. Same problem. Replaced back to my modem & router. Same problem. I can't even watch Netflix HD w/out problems. Can't watch Hulu/Netflix/Amazon & surf the internet. I keep getting the "it's your equipment" or "we have no idea but we want to help". I've made a complaint to the FCC since it's been over 6 mos w/no help. I have at least 100 pics of speed test results, both bad & good, but mostly bad over the 6 mos. I just need the problem fixed so I can use what I've been paying for.

Equipment:

Modem Motorola MB8600

Router: Netgear r6400v2

Log

Time    Priority    Description      02:20:18 Fri Sep 27 2019   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;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=00:40:36:4e:78:dd;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;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=00:40:36:4e:78:dd;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Notice (6)   Honoring MDD; IP provisioning mode = IPv4     12:44:35 Sun Sep 29 2019   Warning (5)   DHCP WARNING - Non-critical field invalid in response ;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:35 Sun Sep 29 2019   Notice (6)   TLV-11 - unrecognized OID;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:40 Sun Sep 29 2019   Notice (6)   DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:49 Sun Sep 29 2019   Warning (5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:49 Sun Sep 29 2019   Warning (5)   Dynamic Range Window violation     12:44:49 Sun Sep 29 2019   Warning (5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:49 Sun Sep 29 2019   Warning (5)   Dynamic Range Window violation     12:44:50 Sun Sep 29 2019   Warning (5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:50 Sun Sep 29 2019   Warning (5)   Dynamic Range Window violation     12:44:50 Sun Sep 29 2019   Warning (5)   RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:50 Sun Sep 29 2019   Warning (5)   Dynamic Range Window violation     12:44:50 Sun Sep 29 2019   Warning (5)   RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;     12:44:50 Sun Sep 29 2019   Warning (5)   Dynamic Range Window violation     12:56:58 Sun Sep 29 2019   Critical (3)   SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:40:36:4e:78:dd;CMTS-MAC=00:59:dc:78:7a:ad;CM-QOS=1.1;CM-VER=3.1;

Apologies if I forgot anything. Just ask & I'll get it posted. Please help!!

Thanks!
Dylan