I could never get my mediator working for more than about 5 minutes with either a voodoo or ethenet card. I spent hours and hours messing about with the position of the mediator and cards with no luck. Tried the cards in a pc where they worked fine, tried on my spare alternate revision 1200, tried diffrent versions of elbox's drivers, nothing. The 1200 would just randomly crash when the pci cards did work, but most of the time wouldn't even see that they were there.
I think the A1200 expansion connector isn't well suited to having several things put on it, an accelerator card on its own can be unrecognised if I move the tower just a bit.
My mediator is just sitting unused in a box now, AGA will just have to do and I bought a pcmcia angle adaptor and suitable ethernet card for the net.