The fact that you have cellular service and 3g makes me lean toward a SIM problem. Either the actual SIM is having a problem or its ICCID has a typo in it, in Unreal's system.
@ Diedrich_Duo: By any chance did you port-in your number to Unreal Mobile? Let them know that you're only getting 3G on your phone. The Moto G4 is LTE capable so there must be something go haywire at Unreal Mobile's backend. They probably have to refresh your account. Once they do that, restart your phone and hopefully will finally get LTE data.
Email or call them...whichever ways convenient for you. During the free trial is a good way to test out how good or bad Unreal Mobile customer service is!
@SuccessOne, thanks for the suggestion! Long story short, my phone has been acting up for about the last month -- it started working everywhere EXCEPT within about a half-mile of home(!!!) -- and I tried everything I could to get it working, to no avail. I finally gave up and bought another phone, which I activated on my main carrier, Twigby, and it is working perfectly.
Once I had that phone up and running I figured it might be interesting to see if I could get the Moto G4 working on Unreal, so I signed up for their free trial, but I didn't port in my number in case there were still issues with the G4. As I mentioned earlier in this thread, everything seems to be working fine on Unreal except for not getting full speed LTE data. (Interestingly enough, my phone won't even let me into any APN settings, so several of the earlier suggestions are "unavailable" for some reason.)
I do plan to call Unreal's customer service to see if they can fix this, but if they can't, I'm convinced that whatever the problem is, is due to something wonky with my G4, not Twigby or Unreal. Worst case scenario, I still have a useful wifi-only device -- I can still use Hangouts for outgoing calls, watch videos, and use all my apps, so all is not lost.
Thanks again (and wish us luck)!