Intermittently Gateway target device failed to respond

Hello everyone,

I am having a intermittently gateway target device fail-to-respond error code from a ConneXium TSXETG100 Ethernet/Modbus Gateway.
This is weird, because sometimes the devices return the data with no error codes.

I have others hosts that also query this gateway.

The Slave devices are, for instance, some PM500 PowerMeters.
I have already changed serial timeout on the gateway with no success.
The amount of queries are really small and above the maximum performance of the Gateway.

Any ideas?

Thanks in advance,
Pedro