MR1100 Not Resolving or Providing Internet

Hi guys, looking for a little support/help on what is truly a confusing issue. Bought a brand new MR1100 from Amazon and got a prepaid AT&T SIM from Walmart, set-up the SIM, and put money in the account. It appears to have the latest firmware installed and doesn't have any obvious defects.

The router appears to be functioning normally and reads as being connected to the cellular network. It's reading the AT&T network on the main display of the router, shows a strong 4-5 bar signal, and I'm able to connect my devices to the MR1100's WiFi network. I don't receive any error messages on the unit itself. However, whenever I attempt to access the internet from the MR1100's WiFi network, either from my cell phone or my laptop, it fails to connect. On my phone, it gives the prompt of "Connected, No Internet" when accessing the MR1100's WiFi network. Every device appears to be connected, but pages just don't resolve. It hasn't registered any data download or upload on the MR1100 display since set-up, but, again, shows 4-5 bars of service.

I've tried a few different solutions from the community forums, including configuration settings, switching over to IPV4, selecting LTE All for bands, disabling the inactivity timers, and adjusting settings per the old Firmware issue, all without success. The only thing that showed a glimmer of hope was enabling data off-loading, as I was able to connect and use the MR1100's network, but I don't think that's ultimately the solution I want to pursue. I just factory reset to start back over.

Any idea what's going on? Is it a configuration issue or a network issue?