Ethernet cable to extender question

Set up 4 wifi cameras for elderly dad. One is out of reach of wifi router. Installed 6100 extender halfway between camera and the camera. Not quite doing it...I get a signal from extender on my phone, and can log in, but camera perhaps sending too much data since streaming video? Anyway if I just do it the ugly way and plug a 25 foot ethernet cable between camera and extender, hopefully that will do the trick . (I think the signal from router to extender is strong).

Any settings I need to know about, since typically that ethernet plug would be used from router to extender to create access point, right? Or does the device just sense its a signal meant to go the other way...back to router? Thanks.

Bonus question- if I just buy another 6100 extender and put it close to camera, will that perhaps do the trick...meaning a cascade between two extenders and then back to router? Can I just set up second extender same way as first and just plug it in, or more to it than that? Thankis.