When I open the builder URL (192.168.1.188/default in my case) on my iPhone it displays a page with the "Install app" button, but when I click on the button Safari (as well as chrome) returns "Cannot connect to 192.168.1.188" ?
I install the b4x certificate (www.b4x.com/ca.pem) and my provision contains the UDID of my iPhone.
I'm using B4i 4.81 with Builder v 4.60.
This happens on iOS 11.25 (iPhone 7), but NOT on iOS 9.3.5 (iPhone 4s)... On my iPhone 4s this works...
Found it in another thread ("While in the settings, I went to the Certificate Trust Settings and realised that the B4i trust was OFF. I turned it on and it installed.").