Here is what happens to a store under different circumstances regarding their internet connection.
A store's internet goes down, and the UberEats tablet is connected to store's WiFi - UberEats will not allow orders for that store as they can not see the tablet while it is connected to the WiFi, which has no internet.
A store's internet goes down and the UberEats tablet connects via 4G - UberEats will allow orders and they will send to the tablet, but must be manually entered to the POS as the Warehouse cannot access the store's back office when processing the order from UberEats.
A store's internet goes down, the modem fails over to a 4G connection, and the UberEats tablet connects to WiFi - UberEats will allow orders and they will send to the tablet, but must be manually entered to the POS as the Warehouse cannot access the store's back office when processing the order from UberEats. This requires a 4G Failover configured in the store's modem.
A store's internet goes down, is running on a 4G Connection, the store has an Imagatec VPN and the UberEats tablet connects to WiFi - UberEats will allow orders and they will go to and show in POS, because the VPN allows the Warehouse to access the store's back office to save the order when received from UberEats.
A store's internet goes down, is running on a 4G Connection, the store has an Imagatec VPN and the UberEats tablet connects via 4G - UberEats will allow orders and they will go to and show in POS, because the VPN allows the Warehouse to access the store's back office to save the order when received from UberEats.
A store's internet is working and the UberEats tablet connects to WiFi - UE will allow orders and they will go to and show in POS.
Internet working and UE tablet connects to 4G which is not working - UE will not allow orders for that store as they can not see the tablet.
The above are all the same if the store is using UE Integration or not so there is no advantage to stores having a 4G failover for UE Integration.
* This requires a 4G failover in the modem and not just connected to the server.
All 4G connections rely on the 4G signal to be strong enough. I recommend at least 2 out of 5 bars but the more the better. Having only 1 bar will not work reliably.
In Summary, Uber Eats Tablets require internet to have UE orders sent to it, POS requires working external access (port forward or VPN) for UE orders to be sent to POS