pod extenders confusing description

Hello - I was hoping the pod extenders would beef up the connectivity in my backyard cottage. I can connect to my wifi just fine and most of the time have all bars.  But when I'm on a webex or bluejeans conference a pop up appears suggesting I turn off video due to connectivity issues.  Sometimes it disconnects from the meeting and reconnects right away.  I was hoping the extender pods would solve but the description says that they don't increase your speed -- what is their purpose if they don't increase your speed and connectivity?

Also, my house is small. 1200 sq ft. one story.  My cottage is in the back yard 10 feet from the house. My xfinity modem is centrally located - I can see the closet door from where I am sitting and yet low connectivity? Is there an issue here or is it because it is in the closet with the dvr, Samsung TV device, blu ray disc player -- too much happening there in that enclosed space?

Thanks