In reality, I already had the following:
From the mixrack to a wall connection on stage 20m CAt5e, then 73m CAT7 house cable, 1m patch cable at the patch field, 25m CAT7 house cable to the FOH floor tank, there again 5m CAt5e to the surface.
In total 124m
I have used this several times and it has always worked stable.
Of course, this is no guarantee, but it shows that the system works quite well.
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