Losing Internet Connection almost every night

That out of spec downstream power may or may not be the root cause of the issue, but it should be addressed regardless. It may be over-driving the front end receiver of the modem causing waveform distortions.

Are there any drop amplifiers on the coax cable leading to the modem ? If so, try removing it and see.

Thank you EG.

I did install a PCT Drop amplifier yesterday.  Before the drop amp it was around 13 dbMv.

Before drop amp yesterday modem  signal would make firewall go to DHCP mode but never get a DHCP address from the modem. 

Will remove the drop amp tomorrow and install a PPC FPA6-54 Forward Path Attenuator 6dB 75 Ohms for DOCSIS Cable TV Box and Modem.

Would this have anything to do with the cable run from the outside to the adjacent house wall box?

Is that + (plus) 13 dB without the amp ? If so, that's still too strong. So yes. Bypass the amp and see. You may or may not even need that FPA. Experiment with both conditions.

Is that + (plus) 13 dB without the amp ?

It was.  Now its lower ...see below...

Removed PCT drop amp yesterday

Installed PPC FPA6-54 Forward Path Attenuator at modem.  Modem never connected after installation of PPC FPA6-54.

I let the modem with the Forward Path Attenuator try to connect for some 15-20 minutes.

Removed PPC FPA6-54 and modem connected fine after a minute or so.

Monitoring WAN link yesterday saw these alerts:  

Nothing before or after.  We were streaming a movie last night from the Internet (thinking it was AOD - Amazon on Demand)

I have been paying attention / monitoring WAN link since going to IPv6 in the last few months.

Modem specs:

Standard Specification Compliant
ARRIS DOCSIS 3.0 Cable Modem / Retail
Hardware Version 3
Software Version 9.1.103AA65L

Mon 4/12/2021

18:59:30 MONITOR: WAN_DHCP has packet loss, omitting from routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|13.267ms|1.276ms|33%|down|highloss

18:59:46 MONITOR: WAN_DHCP is available now, adding to routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|15.906ms|5.549ms|20%|online|loss

18:59:57 MONITOR: WAN_DHCP has packet loss, omitting from routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|16.688ms|7.034ms|25%|down|highloss

19:00:01 MONITOR: WAN_DHCP is available now, adding to routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|15.823ms|5.291ms|14%|online|loss

19:00:04 MONITOR: WAN_DHCP has packet loss, omitting from routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|27.761ms|31.182ms|30%|down|highloss

19:00:12 MONITOR: WAN_DHCP is available now, adding to routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|17.575ms|7.674ms|10%|online|none

19:13:36 MONITOR: WAN_DHCP has packet loss, omitting from routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|18.989ms|11.389ms|33%|down|highloss

19:13:38 MONITOR: WAN_DHCP is available now, adding to routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|17.675ms|10.165ms|20%|online|loss

21:25:23 MONITOR: WAN_DHCP has packet loss, omitting from routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|15.089ms|5.734ms|21%|down|highloss

21:27:26 MONITOR: WAN_DHCP is available now, adding to routing group Failover

8.8.8.8|24.XX.XX.XX|WAN_DHCP|14.49ms|5.424ms|16%|online|loss

I keep seeing these in the event log but I think this is normal eh?

Mon Apr 12 21:28:39 2021 3 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=yy:yy:yy:yy:yy:yy;CM-QOS=1.1;CM-VER=3.0;

Mon Apr 12 21:29:03 2021 3 No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=yy:yy:yy:yy:yy:yy;CM-QOS=1.1;CM-VER=3.0;

Mon Apr 12 21:35:28 2021 3 Ranging Request Retries exhausted;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=yy:yy:yy:yy:yy:yy;CM-QOS=1.1;CM-VER=3.0;

Here are the signals that I see this morning:  (IE: thinking that -15 to 15 dBmV is OK? but reading that -5 to 5 dBmV is better?)

Update 0837C time

From 0800 to 0837 noticed 5 reports of packet loss here.  This reports look like the above ones posted.

The signal stats aren't bad the way that they are now. You could try knocking down the downstream power a bit more if you wish to experiment a little further. But this time, use an overall attenuator pad instead of an FPA. It will balance out both power levels. Try a 6 dB one such as this: https://www.amazon.com/6db-Attenuator-Pad-1-each/dp/B0013L48XA

Would you please post those RF error log entries from the 6190 cable modem in their entirety.

Update: April 21, 2021

Issues mentioned above continue with same almost disconnect messages from PFSense box and same SB 6190 event log messages.

Note these are not 24/7 messages.  Rather they are 1-2 hours at a time; then no messages or event log entries for up to 12 hours...

It is not getting worse or increasing in frequency.  Only it occurs every day at different hours.

IE: today at ~ 17:00C time lost my VPN connection to house #2 (same PFSense firewall and SB6190) where I keep a backup NAS drive and concurrent to VPN tunnel dropping saw same messages from PFSense box and same event log entries on SB6190.

Update:  23rd of April, 2021 0600c time.

Yesterday 22nd of April had over 50 alerts sents to me in the span of one hour with failover messages here.

Just wondering now if my issues are being addressed or when they will be fixed?