Gateway Connection gets switched automatically.

I have a few reports that are scheduled with the "Use a data gateway" option with the On-Premise data gateway(Not personal) installed in my machine. There are a few users in the group who can modify, publish changes to the report. But often I find the dataset's failing to refresh with the error as "Your data gateway (personal mode) is offline or couldn't be reached.". This is because the data gateway connection changed from On-Premise to On-Premise(Personal) which has never been set up and hence is offline. But on one is the group has changed it manually. So I was wondering if there are any situation when the data gateway might get switched. i.e.) Like deploying the report again. I have to go back and change it back to use the on-premise data gateway(Not personal) and it starts to work fine. Finding out the roor cause would really help here. Thanks.