How Can I Systematically Investigate Repeated Security Camera Failures and Strange Wi‑Fi Behavior?

Since moving into our home, we've had recurring problems with several unrelated security systems. Our Google Nest cameras sometimes became disabled and lost recorded history. Later, an ADT system also appeared to disable itself. A wired Night Owl PoE setup had disappearing recordings, cameras going offline, unexpected lights turning on and off, and occasional loss of access. The equipment was eventually exchanged, but similar concerns continued.

We recently switched to Vivint, and the account history now shows that a profile was created and the PIN was changed even though we did not make those changes. We're trying to determine whether this is an account-security issue, a networking or configuration problem, faulty equipment, electrical interference, or something else.

There is also an odd Wi‑Fi observation: inside the house, only two nearby networks appear in the available-network list, while many more networks become visible when standing outside. Other people have independently noticed the same behavior at the property. We are not assuming anyone is intentionally interfering with the network; we want to understand what could cause this, such as building materials, access-point placement, signal propagation, interference, or router settings.

What would be the most objective way to investigate this? Should we replace the router and networking equipment, place the cameras on a separate VLAN, collect router and camera authentication logs, use independent monitoring, have the electrical system checked, or hire a qualified network and security professional? We want reliable evidence of what is actually happening rather than jumping to conclusions about any person or cause.