I purchased the CAX80 end-Dec 2021 and my unit suddenly stopped working in June 2022

https://community.netgear.com/t5/Cable-Modems-Routers/NOTICE-Users-with-sudden-non-functioning-CAX80-modems/td-p/2234550/jump-to/first-unread-message

Also try a 30/30/30 reset on the modem as well. 

DarrenM Could you check the case? 

Thank you for posting this, I am in a very similar situation...

Luckily, I contacted @DarrenM and he was able to get a ticket opened up for me in literally hours of sending him a DM.  To say I was surprised would be like calling a hurricane a "slight tropical breeze," as with most of these replies are negative.

When I contacted Darren, I stated that my router was outside of warranty, but had been working completely fine.  We lost power due to the July flooding in St. Louis and suddenly all I get is a power light.  Nothing worked as far as resetting - 30/30/30, reset (7/10/20/30/60 seconds holding reset), even tried to connect via hardwire.  No Dice.

Darren was able to open a ticket for me with another Netgear member named "King" who was quite helpful and understanding.  Again, I explained the situation and understood that the router in question was out of warranty but it just...suddenly stopped working.  He knew exactly what I was talking about...no extensive trying to reset, no 30 minutes of pointless troubleshooting...just straight to the replacement.  He set up the RMA and all was well - I wasn't going to get another CAX80, but at least I could get a CAX30.  After explaining again "but I am outside of warranty, I dont want to get my hopes up," King said he would still set it up.

Two enthusiastic thumbs up for service thus far.

When RMA contacted me however, Ella was not as helpful.  After sending pictures of my modem and serial # (for the 3rd time, each with the same number and RMA still approved), she quickly replied:

"Good day! My name is Ella and I am a Customer Care Advocate for NETGEAR, Inc. I am writing to you today in reference to your RMA #3716606.

I would like to inform you that we are not able to proceed with the replacement process as we identify that the Hardware Warranty Entitlement already expired last 3/05/2022."

I responded to her asking her where the disconnect was - I thought Netgear was still going to help regardless of warranty?  She never replied.  She did however tell me about how she refunded the shipping cost of the RMA that I was never supposed to be charged.  So I responded to her again, and she ignored that as well.  

Two unfortunate-turn-of-events thumbs down for service.

I understand how frustrated I sound, and I am sure you may or may not be approaching the same level.  I understand that Darren, King, and Ella do not set the policy at Netgear and are only the people who get paid to enforce it.  But it seems as though there is a standing problem with the CAX80, so widespread that its even getting some attention on fringe websites (https://piunikaweb.com/2022/07/28/netgear-cax80-modem-router-bricked-or-not-working-for-many/).

Hopefully there is a happier ending for you than there has been for me.  Until then, I will continue to try to contact the same folks who seemed to want to help me before until someone at Netgear tells me "no, we will not replace your modem that suddenly stopped working regardless of if you treated the $449.99 piece of hardware as if it were made of glass" or, hopefully "hey, you're right, let us fix the issue so you stay a life-long Netgear user."

Fingers crossed, I dont want to have to buy Motorola.