Most secure router

I see a discussion on fastest routers but nothing on which may be the most secure. I am a CenturyLink customer and my modem brand is limited but I can add another level of security by using a router not to mention a mesh router would give me decent coverage for all my IoT's. I need a high level of security as we have a family member in Army intelligence who has been hacking into our computer. Any suggestions would be appreciated. We are a mostly a windows based desktop with Apple devices and as I mentioned many IoT's.