@ddebasilio Did you figure out the issue?

Because I am planning to do the same setup after I found out that E4 only support 100mbps and I can not return it.

@Muji 

After I destroyed the mesh and started over by setting up first the M4 I did get higher speeds but never close to 1gb. It works around the 200mbps going down the further you are from the first access point. I deemed it sufficient since I have multiple devices and it served as a accidental QoS, but it is not perfect. I am quite disappointed that I didn't originally just buy M4's because there are times when a 1gb over wifi would be great.

@ddebasilio My internet speed is 200mbps but I only get 95mbps with the E4 setup. I'll get an M4 to connect it to the main router hoping to get something near the 200 speed. I wish I knew about this before too. I would have gotten all M4s instead. 
 

thank you. I hope it works.