Dooorbell WiFi issue and stuttering

Hi, I recently got my doorbell. It’s good but there as a few issues.
I’ve connected it to a WiFi extender and the live view and recordings are quite stuttery. I changed video to begin but still the Same. Has anyone found a workaround?
Also, my WiFi appears to go from 25kb to 200 back to 50 etc
Them router is too far from the door so I use an extender. What should the WiFi be getting to have smooth footage?