Unkown message when working with a new meter

Hello, I'm working on an AMR project (C language) and recently we received a new meter to work on and sometimes this meter sends a message that gurux cannot translate.

First of all this is the message:

7EFF0300230003C003808F2C7E

Gurux translator doesn't give me anything (we're working without any encription and authentication for now, so message should be clear).

We observed this message on two instances, first one sometimes the meter sends this along with another message, for example if we send a connect message the meter will answer with this and then the connection answer in a row (almost at the same time, the second message comes when our firmware didn't even proccess the first one).
And other times the meters sends this when we're not even communicating, our firmware is just idle and not expecting anything and the meter send this same message.

Do you have any idea what it is or how I can find out? That's the first time we've encountered a situation where the meter sends data when our firmware is not making any dlms operations. Just to clarify we can normally do operations like connect, read, write, disconnect, set method.