At the location of OWL check whether the specific mobile network can be received by other devices. A good idea is to use the SIM of OWL in a mobile phone and check if you can perform a phone call etc. Make sure that you use the same technology for this test, e.g. 3G or LTE, ...
Usually the reception of a network using OWL is better than with a mobile phone.
If the mobile phone doesn't offer the service, then check with prepaid card if you have enough credit.
Please note that interrupts of connections are usually caused by the provider in cases of high load conditions at a specific cell. Your OWL might be even roamed to a far away cell by the provider when the provider expect this as appropriate.