A forum specializing in NETGEAR Wi-Fi would probably be a better spot to discuss this. (The forum you posted this to is mostly app development questions for third-party app developers, and developer program membership issues. Not the prime place for knowledge of NETGEAR weirdness.)
I’ll assume the NETGEAR Wi-Fi router has been factory reset and the latest firmware loaded, and that the latest firmware update isn’t ancient. If it’s still flaky, it’s usually either the Wi-Fi router itself failing, or maybe interference, or a security issue.
Wi-Fi diagnostics on macOS or on Windows are helpful for spotting common Wi-Fi interference issues. I use the add-on Wi-Fi Explorer app for that purpose on macOS, as the display from that app makes it very easy to see what is going on.
If the Wi-Fi password itself is actually changing, y’all have a local security problem with your hardware access or Apple ID or passwords or such, or have an exploit.
NETGEAR has some CVEs, too. A quick scan finds CVEs from the last couple of years. Current firmware and current device updates matter, here. “Abandoned” devices can have known issues.
Here? I’d consider replacing the Wi-Fi router. USD$200 is most of the way to a nice Synology Wi-Fi router (RT2600ac) with Time Machine support (hard disk drive extra), and there are other good Wi-Fi options available.
There’s no way I’d spend that much for a service plan on an existing and semi-working Wi-Fi router, either.