Just realized my old router was a security hole for 4 years
I checked the firmware on my Netgear R7000 from 2019 and it hadn't updated since 2021. The vendor stopped supporting it after a breach notice in March, so my whole home network was exposed on ports I didn't even know were open. I swapped to a $90 AX1500 from Walmart and ran a free scan with Nmap, found 3 open services that are now gone. Anyone else running gear past its support date without checking?
Worth noting that Nmap only shows what's listening on your new router, not what was actually exposed to the internet before. Ports open on the LAN side are normal, so what really matters is whether your old router had remote admin or UPnP turned on and facing out.