Apple browsers (MacBook, iPhone, iPad) not working consistantly

Purchased a new Router (Nighthawk AX4300 Model: RAX45-100NAS) from Costco last week to help manage all the new devices on the network with everyone home during the Safer-at-Home order.  We are have a heavy amount of Apple products on the network (MacBook's, iPhones, iPads, Apple TVs, etc), network printer and a few Microsoft laptops. Took an eveing to get the new Cable Modem installed (Nighthawk CM1100 Multi-Gig Speed, Model: CM1100-100NAS), changed our service with Spectrum to the 400/20 plan, and Router installed, frimware upgraded ( v1.0.2.10_2.0.26) and configured.  And turned off Coexistance, per others suggestions on the NG Community.

We quickly noticed the apple devices were NOT not loading webpages.  At first, I thought the devices lost their internet connection.  After closer examination, items in the background needing internet access where working without issue.  If we utilized various VPNs, no issues with browser data loading.  Turn off the VPN and issues would reappear with data itermitatly loading in browsers.  Safari appeared to be the most severly impacted, but we also saw the issue with Firefox, Chrome and IE.

I spent a few days trying varoius solutions and coutless reboots of the modem & router, but to no avail.  By chance, I disconnected an iPad from the network, closed all programs, cleared the Cache, Cookies, and History, and rebooted.  Upon reboot everything worked like a champ - NO MORE ISSUES.  I did the same with the rest of the devices and all is well - no more browser loading issues!!!

Looking back, I suspect there was possible DNS issue with the new router and the historical cached information on the devices causeing the browsers to not load data properly.  Regardless, putting this out to the NG Community in hopes others will benefit.  Since resolving the browser issues, the system has been rock solid and blazing fast as we are seeing speeds in excess of 450/25 (above our aloted 400/20 plan).

Good health to all...