Update a couple days later: Still running fine... (One wired laptop and one iPhone with Static IP, 2x Roomba vaccuums set as DHCP - set to this router) .. Deciding to push it somewhat, as I've done with mine - from the get-go, I set TP to process ALL PACKETS..... Not the Default... No issues with that, so today I pushed further..... On my main 2600 in TP, I have over 200 Self Defined rules, as well as many edited to "Drop" groups -- so Backed TP up on my main 2600, and imported them into Neighbor's (Both 2600 Set for same IP - So all custom rules would apply). I had tried this an hour after updating, (USB2 speeds) and it took forever, so I aborted it then..... Today, changed Router Drive to USB3 speeds, and tried the Restore again... It finished in 16-17 min.... Testing continues..... (And Roomba's at 2.4Ghz WiFi connect fine-Vacuuming now!) No issues seen so far......
I'm beginning to think Her ISP was down, and they blamed router.... and by the time she went to Geek, and bought new router, and installed, ISP was back "UP" !! (They did that before - when during Helene a landslide beside her house took out the cable feed from road above her house, and Support said they 'saw' her modem (When No lock lights were seen), but when I fiinally made it up her half destroyed road with AWD Vehicle, we found the orange cable severed 12' from her house, and orange cable dangling from pole 300' away, with a landslide in the middle (She's still awaiting the FEMA approved fellow to come and stabilize the hillside!) THEN when I called Spectrum Support for her: Support admitted they didn't 'see' modem, and issued a trouble ticket !!!!! (

poop:

GRRR!!! ????)
I've added velcro 'dots' to bottom of 2600 router such that External SSD for TP & Logs is mounted with ventilation space under 2600, And a 'Clip-on' RFI Ferrite bead filtering a couple loops of USB cable, attached just outside of view, as done on my other 2600's -- All neatly mounted underneath the 2600.. this cleans up the "look" of the router,as well as prevents inadverted "dusting disconnects", with only a loop of USB cable indicating that something is attached to 2600.... and drive not just laying on desktop beside router. ( PS: that label has both new admin and WiFi's Log-in & Passwords, with default admin login deleted!)
Long term testing continues!

!
PS: no VPN, VLAN, Guest WiFi, or mesh: All 3 2600 routers: CPU (35-45%) & Ram 45-50%) used are identical