CAX80 Modem Router, Mult-Gig Ethernet port connected to RAX120 router causes internet disconnects

[doug2222]

I have a Nighthawk AX6000 DOCSIS 3.1 WIFI 6 Cable Modem Router (CAX80), connected to a Nighthawk AX6000 WIFI 6 Router (RAX120) via the Multi-Gig Ethernet ports on both devices.  

problem, any wired or wireless device connected to either the CAX80 or the RAX120, get notifications, Internet Disconnected, every few minutes.

searching the database, i find that other customers with the CAX80 experience the same symptoms, after receiving firmware update 2.1.1.4

searching the database, i find the only solution is to not use the Multi-Gig Ethernet port, and use the 1GB ports between units.

calling technical support means sitting on the phone for hours to hear they dont know whats wrong.

i purchased these units for the Multi-Gig port, on an order that totaled $1000 in equipment to reequip my home.  

in addition my order was shorted an item and their responce was to tell me im lying. i had to reorder the missing unit, an extender EAX80. (that was not connected during this problem)

is there a firmware upgrade, settings adjustments or work around to allow these two units to use the Multi-GIg Etherent connection without the disconnection problem.

[FURRYe38]

What mode is the CAX80 running in? Router or modem only mode? 

What is the cable condition of the LAN cable in between the CAX and RAX? CAT6 is recommended. Try swapping cables as well for known good working cables. 

[doug2222]

cable is probably a cat5 so i will need to get a 100 footer and replace it.

mode i will have to check. think its router on both units.

cable doesnt matter as others having the same problem have had Cat6 cables and their routers had the same symptoms after firmware update 2.1.1.4

[FURRYe38]

Ya CAT5 isn't supporting of anything over 100Mpb per spec. At least 5e but CAT6 is best. 

Lets check modes on the CAX. Would be a good test to see if modem mode on the CAX and RAX in router still happens. 

I may put my CAX back online and take another look at this as well.