CAX30S and EAX80 Not Connecting

This is the first time I have set up own internet modem/router combo and an extender, and I have been running into a series of issue through out the first couple of months of setting it all up. Here is what you need to know:

• ISP: Xfinity
  • I chose the CAX30S as it was in the list of compatible devices with Xfinity Internet and my subscribed plan.
• The intended plan was to create a Mesh Network for myself and my roommate(s) with the CAX30S on the 2nd floor, and with 2-3 EAX80s spread around the houses and each of the 3 different floors.
  • Spoke with some technicians from Xfinity and basically gave up on the Mesh idea so I am using them as standard Extenders
  • While the EAX80 on the 1st floor (distance wise right below the CAX30S) is working fine, the EAX80 on the 3rd floor seems to have connection issue(opposite side of the house from the Router).
  • Have attempted resetting and rebooting the Extender to minimal results.
• Used the Shark App to setup both router and extenders.

Let me know I missed a step or if there is any other ideas. Thanks.