Orbi + Circle Custom Filters Support and CATS app

So I have been adding domains via Circle Custom Filters to help keep undesireable content filtered from my kids, but I have finally met my match. I usually use Charles Proxy to log requests from my kid's phones that have challenging connection problems that cannot be solved by browsing History and adding filters from the UI.

My kids want to play the game C.A.T.S. on their phones, but the app will not start while they are in Adult (or Teen) Filtering mode. I discovered that there is a call to:

balancer.bb.zeptolab.com:7710 

that is being blocked while in Adult (or Teen) Filter mode, despite adding a custom filter for that domain/sub-domains. I have added it with the port number and without the port number.

balancer.bb.zeptolab.com:7710 

balancer.bb.zeptolab.com

The Circle documentation doesn't say if it supports port numbers or not, but the user interface definitely allows for it to be entered. Regardless, I am unable to bypass this call unless I turn off all web filtering for my children. 

Does anyone have any suggestions for things to try out?