I had similar requirements and fell upon mesh central. To keep it secure on web I have it hidden behind cloudflare tunnel and an access policy.

Bonus points it even supports mobile devices if you need to help your mum with those too.

Another one I was a fan of was level RMM if you can stay below the 10 device limit it’s completely free - all hosted on their cloud. I have too many children so had to switch from level.

I just sent a ddos attack to his ip. In an unrelated event my doorbell camera has stopped working?