adds ZERO to page URL

I don’t think AddFunc Mobile Detect will work for you if your mobile pages are at the same domain name as your desktop pages. That “0” might be an indication of a redirect loop, perhaps. I really don’t know. This plugin is for setups where your desktop site and your mobile site are at different domain names, or subdomains, but not sub/child pages. I’m curious how you got it to redirect to your child pages though.