Wireless access in a Faraday Cage

I’m installing wireless internet in the hotel I work in and have a problem. I have half of the building where the signal drops to Zero within 50 feet of the router. The other side of the building was relatively simple to provide coverage. I’ve tried wireless repeaters and they only work for a few feet in this zone. The problem is the rooftop lightning rods crisscross the roof and runs down the south elevator to ground. Plus, there is an amazing amount of aluminum duct-work running through this section. Any ideas?