Almost weekly there’s an UNKNOWN device on my router. It is not any of my devices which are only two devices I use on my Wi-Fi. How is someone hacking into my router on a continual basis? I change my password and block their Mac Id but they come back with a different ID after a few days.  I change the admin login password weekly, I wish I could change the login from admin but seems I can’t. I change the Wi-Fi password and was only using the Guest Network. Currently, I’ve connected my streaming device, computer and iPad to Ethernet but would like to still use my Wi-Fi for my security cameras. That’s probably how they’re getting in. 
 

Any ideas to make my SBG more secure?

also every time I login there’s a box asking me to register my router, which I had already done and I click to stop asking and it’s still there when I login in the next time. Also when I change my login password, it always given me an error message of some sort but when I go to login the new password is being used even though I get an error message that it didn’t work. I’ve reset my router but that didn’t correct the problem. Do I need a new router? Maybe a different brand?