I was experimenting with Redstone Links and Extractor Links, and it appears that my server is now bugged and I can't link Redstone Links anymore, they do not communicate on the same frequency.

You have to shift-rightclick with an empty hand on the receiver link. If you see a little iron dish on the antenna it means it is on receive mode instead of send mode. only by having a sender and a receiver with the same frequency it will work.