i was going to purchase a new router today during lunch until i found this. i was facing similar problems like OP. i was on the new beta 3.3.535. i dont ever touch the settings.i dont even game tbh. i just made sure i was getting the mbps im suppose to through spectrum and im good. but the past few days, i kept getting a "you are no longer connected to your router..." bootloop. i knew about nmrpflash but i dont like doing command line things. i tried tftpd 32 and 64 and i get the same bootloop. was gonna try those other firmwares that the cool kids are tinkering with but didnt want to deal with this router performing lower than stock firmware. even though, during the flash, i got a warning: tftp block rollover message but everything worked. im not sure if i should stick with 2.3.2.134 (since im consecutively getting the mbps im subscribed to so far), go back to beta 3.3.535 or look for a "things i must do after installing...." list to get an even better performance. either way, im happy. alot of others have this same exact problem but none mentioned nvmpflash. i even saw someone saying to let the router sit in 91% isopropyl alcohol.
maybe someone else that has the same issue might find this simple fix.
thank you for the recommendation.