Thank you for the additional context.
Echoing @drm186, Waverly (and most of Iowa) is a bit of an oddity for coverage with Republic’s GSM network partner. Generally, coverage in Iowa via Republic’s GSM partner is provided by iWireless, which is in turn an affiliate of that GSM partner. Said GSM partner has recently completed outright purchase of its affiliate iWireless but coverage is still considered to be provided by a partner (roaming). Eventually, I expect this will change but we’re not there yet. When coverage is roaming (provided by a partner of Republic’s partner) there is no cell data available for Internet access.
CDMA (Sprint) coverage looks to be hit or miss and arguably more miss than hit. That said, the coverage is native (not roaming), so where available so too would be cell data for Internet access.
Lastly, and I don’t say this lightly, you might find coverage to be better in Waverly with AT&T or Verizon. Should you or your daughter decide to investigate that, please know her G4+ is North American factory unlocked and can be activated on those networks.