At a loss. Wiring a possessed house I think! Input needed

Question

Need some help.
I know and have done a lot of networking No pro, but self taught. Did run Ethernet of my whole house (ex wife's house now ) pre wifi days. Running wires, using switches and routers. All worked. Have down a ton of wifi - all Apple gear for myself in my location, friends and family. Good to go. I currently run a bunch in my home for iPhones, computers, netflix, itunes server, Air Video for all devices. Flawless.
So I'm not a dummy at least. So……
To my dads house. My on going project for a year. Great house. Big. Hand built back in the '50's. All plaster. Well made.
1- His office - cable modem to Airport Extreme - named BASE. Across this room, one Airport express (all AX are older g units) for the stereo from computer.
Now when I try to extend this network only for him to use his iPhone with Apple Remote to control music, I have now bought 5 Airport Expresses - the signal will not carry for more than 10 feet at best in this house (it's possessed I swear). NOT KIDDING.
I put an Express 10 feet from the office to a kitchen, why because any further I get no signal connection.
From this Express another one 10 feet for a den.
But the signal is so weak it doesn't work.
The house is plaster - I guess very well plastered and who knows what metal lathering is behind the plaster? It's a ranch.
What could possibly abort wifi signal like this. Oh, I might add, no iPhones work in the house either. We're in NY.Long Island. Major ATT signal. Nada in house. Go outside no problem.
So I'm going to tackle this again this weekend. Start from scratch. Any insight? I'm asking because I'm at a loss and think I'M NUTS! LOL
What would make wifi not carry for any distance? Lot's of windows in the house too.
I'm on the verge of telling him to have cable run another wire and modem to the other side of the house.
I'm stumped. I was going to post a few times but can't imagine why I can't get this working. Feel like a dunce.
Right now he tells me it's no connection in the den. The last AX extender not 10 feet from him.
Thanks in advance.

Answer 1

In addition to metal, water also will cause significant reduction in signal. The higher the frequency, the worse the problem. (One of the reasons why in the past submarines needed to surface to use their radios.) Perhaps the plaster or wood is exceptionally wet or the particular plaster they used has a high metal content. You may want to try using only 2.4GHz instead of 5HGz because lower frequencies penetrate walls better. I'm grasping for straws, but I'm not sure what else you could try short of tearing down walls.
I will tell a story of one wiring job I did. My boss gave a quote and approval sight unseen. He normally didn't do this but due to various circumstances and time constraints, he took a gamble. The job was to install a DSL modem and wireless router for a doctor's office. The modem and router were in the managers office. The reception area in the next room would have two workstations about 15 feet away, connected wirelessly. The doctor's office would get one laptop connected wirelessly, about 100 feet at the other end of the building. The building was all wood construction so no one foresaw what happened next. The manager's computer was fine since it was wired. One of the wireless reception workstations was fine with full signal strength since it was a line of sight through an open doorway to the router. The other reception workstation was working but only had 50% signal strength. (Not line of sight to the router.) The doctor's laptop had zero bars. I moved the laptop next to the router and got 100% signal strength. I walked the laptop next to the workstation with line-of-sight, and still got 100%. I walked to the other reception workstation and got 50%, same as the workstation. I walked out of the reception area turned left and started to walk down the hallway to the doctor's office. I took no more than 5 steps and got zero bars! I walked back a few steps and the meter jumped to 50%. I had to do this a few times to fully convince myself. It was only a chance conversation I had with one of the nurses who recalled that the former occupant of the office was a dentist. So we surmised that the room that the router was in might have had the x-ray machine, so they would have lined the walls with lead or whatever. In any case, we ended up having to pull wires. But we learned that regardless of what it looks like on the outside... But this does sound quite similar to your experience.
There's also the time that my coworkers found that the whole wall was 1/4" steel plate. The walls were covered with drywall so we didn't know it was there until we ruined a half dozen drill bits. It seemed like it was armor plate steel. We think the building used to be a indoor gun range or something. And there was the time that we encountered hardened concrete walls at an office using a former military building. Fortunately neither of those had Wi-Fi but we likely would have had signal problems in both cases. It taught us that we can't assume and needed to do a thorough inspection ahead of time.
So while I don't think the house is possessed, I do suspect that the original builder used some funky local material. Maybe he was a conspiracy theorist and has tinfoil in all the walls.