how can I secure my router from my gf son from changing settings to enhance his wifi signal?

AtWittsEnd

My gf son stays here at out house and changes settings to enhance his wifi signal which causes all our other equipment to drag, stop etc..  He is a wiz at computers and has come in backdoor although I have blocked his Mac address, his PC, anything associated with his computers.
#Others_Nov_2018

AtWittsEnd

Also I have password protected the router to no avail. Is there a way to block him completely form getting into the router?

Mijzelf

When a person has physical access to the router, nothing technical will stop him from just applying a factory reset. In that case no password can help.

Maybe you should have a good talk with him.