Hello and welcome to the forum
Your problem could be due to several issues, but we need more information such as which model of freesat do you have.
I would check carefully the LNB cables into the Humax for poor connectons. If possible swap the cables over from the working and non working devices, and see if the fault follows the cables. This might indicate a failing LNB or poor connections at the LNB end.
I am still running a very old, but reliable Foxsat HDR so I’m not really familiar with the later model’s. Once we know which box you have I’m sure you will receive more advice.
Good luck
Les