No PLC-link between units

HI there. I hope someone can help me.

I bought a pair of these units a few weeks ago.

Set up was easy. and it worked fine,

A few days ago it stopped working  “No plc link”

I have tried to resync but to no avail.

I have tried a reser, then resync this didnt work either.

I have tried different ethernet cables and different ethernet ports, but this didn’t help.

Can anybody help me please?

Thanks in advance