For the last month+, DNS issues and dropped Wi-Fi (now using R7000P)

Hi all! 

I've had a horrible experience with my Netgear router(s) lately. I was having DNS issues (now I suspect it might have been a FW update, as it corresponds to roughly the same time the new FW came out for AC1750), and I even changed ISPs (from DSL to cable), and it didn't resolve the issue.

Last week, I upgraded my router to the R7000P (previously had AC1750), but the issues persist AND my Wi-Fi is dropping from my 5GHz network, but the 2.4 GHz network seems stable. 

Here are the errors I have been getting:

• ERR_CONNECTION_RESET
• ERR_NAME_NOT_RESOLVED
• ERR_CONNECTION_TIMED_OUT

I did everything in this article: “ERR_NAME_NOT_RESOLVED”: How to fix the Chrome/Android Error? - IONOS. I changed my 2.4 network to channel 11 and my 5 to channel 161. I have switched between ISP provided DNS servers, to Google, to Cloudflare, and back to Google.

After spending 2 hours on the phone with Netgear support yesterday, I ending up rolling back my firmware to V1.3.2.126_10.1.66. I did not reset to factory. Should I have done that?

What else? I am trying hard to stay cool right now, but this is super maddening—especially after a two-hour phone support call that didn't resolve the issue.

My understanding of these typs is technical issues is rudimentary, so please expand on solutions, if you're able.

Thank you!!