Thank you for the additional context! Your E4 Plus does have different coverage than that of previous generations of Motos running on Republic. That said, according to the coverage map GSM coverage is supposed to be good. I suggest you try the following:
Refresh your phone’s, Republic activation as described here: How to Refresh the Republic Wireless Activation – Republic Help.
With that done:
At Settings -> Data usage; please be certain Cellular data is toggled on.
At Settings -> More -> Cellular networks; please be certain Data roaming is toggled on.
Lastly reset Network Settings. Please know this step will clear out any saved connections for WiFi and Bluetooth. To do so:
At Settings -> More -> Network settings reset; read the warning then tap “Reset Settings.” You will be warned a second time. Tap “Reset Settings” to confirm. The process will usually take 5-10 seconds and the cellular signal bars icon will go away for a moment. Once the cell signal bars icon returns, please restart your phone.
If the coverage experience still doesn’t improve I would then suggest you ask Republic for a SIM that will give you the same coverage as you had on earlier generations of Motos: How to Request a 3.0 CDMA SIM Card – Republic Help.