Talking about walls today I checked and found out of the 4 walls coming in the path of the router and my S4 each concrete wall is of 6 inch thickness and the last one being 11 inches in thickness. And today I went outside my house on the road right next to the room where the router is placed (a 11 inches concrete wall in between) and found that I had connectivity till 262 feet from my house on the 2.4Ghz band after that it lost the signal. So is it normal?
Sorry for my earlier post, I just read these two.
You are asking WAY too much of the router. Multiple concrete walls is going to kill signal. Especially 5GHz, but 2.4GHz as well.
If you read my prior post, I have a 4ft cinderblock and stone fireplace (so it is partial hollow cavity with the cinderblocks, actual masonry thickness is probably closer to 14-18 inches) and it drops signal strength by around 18dB,
3 concrete walls a 6" of thickness each plus an 11" concrete wall probably adds up to at least 30dB of attenuation, if not more. Plus roughly 50ft of distance, and not knowing the coverings over the concrete (I assume they aren't bare concrete). That is probably pushing you in to -70 to -80dB of signal strength on 2.4GHz. By comparison I have -76dB of signal strength laying in bed from my living room router on my laptop with resonable sized antennas. That is 2-3 bars according to Windows and I can connect at around 24Mbps and get a usable 1.5-2MB/sec on my laptop. My iPad 2, which probably has similar gain and Tx power to your S4 would connect at 1 bar, sometimes dropping the connection completely, occasionally I'd get 2 bars for a second before dropping. I could get a usable 200-300KB/sec usable throughput on my iPad. That is through that chimney and 4 regular 2x4 walls and only 40 some feet.
That is less distance and a lot less obstruction than what you have going on.
You need a second router in your residence.
Open air distance doesn't do a lot to impact signal strength. That same living room router I can connect at -62dB at my mailbox 150ft away from my router, but it is directly visible through my living room window, so direct LoS with only two panes of glass (not low E) in the way. Out the rear of my house, at a similar distance from my router, I connect at -76 to lost connection (inSSIDer shows to about -85dB) depending on exactly where I plant my feet, but that is through an exterior 2x4 wall, insulation which is FOIL faced (1960's house) and a layer of wood siding with a layer of foam insulated aluminum siding on top of that.
So effectively that one exterior wall added 14-23 dB of extra attenuation (that means that the signal is about 21-200x weaker) at the same distance, just different partitioning between me and the router. Its also why I am placing an access point in my garage with the antennas mounted through pigtails on the exterior wall of my garage to remove any obstructions from where I need Wifi in my backyard, so it is all open air (and ~20ft closer to the location, which doesn't hurt either).
2nd access point man, 2nd access point.