XB8 issues

I recently tried to upgrade my Xb7 to a Xb8 with no success.

1st attempt; Xfinity sent me a Xb8 modem by mail which I installed myself and immediately had Wi-Fi issues. I then called Xfinity tech support who then ran several tests and couldn’t find the problem so they arranged a service technician to come to my house a couple days later.

 When the technician came he did several different tests with the modem, line and said it kept cutting out on him and was going to replace it with another.

 
2nd attempt; The technician brought in another new Xb8, installed it and again it started having Wi-Fi issues with not being able to login with the SSID. He then went to the main coaxial splitter and said he thinks that because the splitter was a powered splitter it’s interfering with the modem and tried to use a regular unpowered splitter which then disabled my MoCA network adapters that went to different devices to different rooms in my house using coaxial cable.

The technician then said it was either the powered splitter or my MoCA adapters that weren’t letting the Xb8 work correctly, so he put everything back the way it originally was and reconnected my older Xb7 modem. Every thing worked fine after going back to my Xb7 but nothing was resolved on why I can’t get a Xb8 that works correctly with my MoCA network adapters. 

So do I have no other options of upgrading my modem?????