1 internet 2 routers to extend range in an apartment
 

Here is my current setup

Modem in Room1 --> AC Wifi Router 1 in Room1 --> Cat6 LAN cable goes inside the wall to the TV in family room.

I didn't realize 2 thin concrete walls will drop the AC & N signal entirely in the family room. As I have a spare 2-port AC router, is it possible to do the following?

Modem in Room1 --> AC Wifi Router 1 in Room1 --> Cat6 LAN cable going to family room ---> AC Wifi Router 2 ---> Cat6 LAN cable to 4K TV --> everyone in the family room can get wifi

My questions are, Router 2 needs to setup as extender mode? Will I get both LAN, AC & N signals from Router 2? SSID cannot be set as same as router 1?

SSID can be set the same, the computers are smart enough to hand over to the router with the strongest signal.

If you want Router 1 to reach other rooms, you should set your rates lower. 5ghz doesn't penetrate walls as well as 2.4.

Router 2 should be setup as Bridged mode, basically you set the gateway etc as if it is another PC connected to Router 1.

It depends on which firmware your spare router has. OpenWRT or Buffalo is the most flexible.

Out of curiosity are you exclusively using the 5Ghz band? I did the same in my 850sqft condo and it was terrible in the far reaches.

Once I moved to the 2.4Ghz band in the bad areas I was getting full coverage.

Before you buy another AP, try playing around with band channels in case the channels you're using are close to saturation. (Note: I'm not an expert in this area, and I've only read about it in passing)

some of my devices can only cover channel 36/48, I have limited choice.

I want both 2.4ghz and 5ghz...my security camera and TV can only do N, but others are AC. I am trying wireless extend mode (which somehow easier to setup) and only get either mode (N or AC, can't extend both)

I believe there more than just being smart, there's a setting you have to change/tweak for your wireless card, how aggressive your network card is roaming. This setting should be easily accessible on a PC, but probably not available on most mobile devices.

SG :: How to set a Wireless Router as an Access Point

I followed this site to "bridge" my second router.

I would recommend you separate your security system from the rest of your devices by a separate router. Wifi hardware ise gives each device equal time, assign each system into their separate network, to level out congestion.

Most commonly, devices will stay with their connected AP until the signal is too weak to be usable even if there's a stronger, they will not automatically switch to whatever AP signal is strongest.

To get that level of functionality, you need routers with "Zero-Handoff" capability. Usually only found in commercial grade stuff. I think some of the higher end Linksys stuff is starting to get that feature.

I have a DLink DIR-880 router in my house (towards the front of my property) and one in my detached Garage (at the rear of my property). When I had them both set up as the same SSID I'd frequently get my laptop automatically connecting to the house over the garage when I was in the garage evident by a really weak and slow (but working) signal.
I now have them set as separate SSID's that I'd manually select depending on where I am, and it avoids that problem.

There are 2 issues here.

On the AP side, most routers hand off correctly IF the APs share the same SSID AND are set to the same channel for all the routers. (So Auto obviously is a non starter), pick the channel wisely. The driver typically compares the RSSI of the same channel to decide which AP to go with. For Ubiquiti hardware "Zero Handoff" basically is a configuration check to make sure both criteria are met.

Apple Airport (RIP) works, so will any router that runs OpenWRT eg Buffalo, Ubiquiti, Cisco etc.

To answer TRD comments. Some Android devices don't have a library bgscan installed properly on the linux side, that would prevent network switching based on the RSSI levels.

If you are using multiple routers with the same SSID, you should be using a different channel for each router.

It depends on the geography, as I said if you want zero handoff, they need to be on the same channel.

just get ubiquiti Ap devices which will handle the same SSID for all the units and channel selection for you instead of using wireless routers

so which one is correct answer? lol

Here is what Ubiquiti has to say about zero handoff:

For most purpose, same channel or not it will work, same channel means the utilization will be higher.