NETGEAR WNDR3400v3 1.0.0.48 repeater

I forgot to add that I would like to configure the same SSID for the 3 devices

You can use ethernet connection to bridge wifi network, no need for wifi repeating.

Preshared password means WPA2-PSK ;)

asker doesn't want WEP  but was only previous option.

Hi gheist,
You can use ethernet connection to bridge wifi network
I am connecting the Wireless routers to the switch through ethernet but If I don't configure them as repeaters then how Do I have to configure them?
Disable dhcp and configure an static an ip address? I did that on the past and gave me issues with users wifi connectivity that's why I configure them as repeaters.

Hard to tell about wifi connectivity.
All you need is to bridge wifi clients to ethernet wire where home-style software router offers then NAT and DHCP.

David Johnson said:
configure them as access points (you've already got them connected via ethernet) using the same SSID encryption type and pre-shared password

OK I configured the 3 routers with same SSID, encryption type and pre-shared password and it seems to be a conflict with the 3 of them.
I have an exclamation mark on my wireless connection so I decided to disconnect 2 of them then suddenly I am able to connect to the internet but the moment I connect a second one I loose internet connectivity and the wireless connection gets a yellow exclamation mark and I am not able to browse the internet.
I need to make it work by tomorrow noon, any advise will be appreciated.

Run some wireless survey tool like InSSIDer v3 and make sure they are on different and less noisy channels.
By different I mean 1-6-11

So my question would be: Can I run the same SSID on the 3 Netgear N600 without issues? I will run InSSIDer and  change the channels on every AP tomorrow morning. Thanks for your quick response

I run some 10 Cisco APs and 10 OpenWRT APs with same set of SSIDs with different channels on nearby APs. Clients roam freely between APs and there was never a problem in the air. Can you check is you disabled all WDS and range extender features completely (maybe it needs full AP configuration reset)
Also if you export/import configuration make sure you dont clone MAC address.

Thanks for your advise gheist,
I run inSSDer to check and configure 4 NETGEAR N600 as access points, I choose channels 1,6,9 and 11 using the same SSID name and when trying to configure a 5th one users start loosing connections to the WIFI. I need to configure a fifth AP for the conference room but I don't want to run into the issue of people disconnecting. Also I have users not been able to connect to the WIFI AP.
What's your advise on this one?
Second question: What about if channels 1,6 or 11 are very busy? because I search on the internet and every body says those are the best channels to use. Can I use any other channels like 2 or 3,4,5,7,8,10?
Please advise

in the 2.4ghz band there are only 3 channels that don't overlap other channels and these are 1,6,11

So you mean that those are the only channels I should use when using 2.4ghz?

So you are saying that the only channels that don't overlap are 1,6,11 but what about when you install 5 Access Points? I tried to assign those channels as follow 1,6,11,1 and 11 and my connections start dropping, then I assign to the 4th AP channel 9 and removed the 5th AP. I need to add the 5th one but it will drop my connections.

Then you are adding too many access points as they are overlapping too much..  You would add the channel that has the lowest signal strength at a location.

This is the longest explanation:
https://documentation.meraki.com/MR/WiFi_Basics_and_Best_Practices/Channel_Planning_Best_Practices

(Yes, you need to have long distance between APs, so that next AP's location barely receives brothers signal. It is different than WDS you used to run)

So you call WDS the way I am running this routers? even each router(AP) has their own ip address and they are connected individually to a port switch?
So at this point I still have issues with users getting disconnected and users not been able to authenticate on certain spots. Will you suggest on getting a real access point to extend the signal? or  I have to fine tune using the inSSDer 4 which I have purchased.
The office square foot is 3,900ft.

Thanks for your help. Got it working. I realized as you described that I had to use INSIDDer but choose the channel manually, One of the APs had channel 1 but it was the one not authenticating any users and connections been drop. I changed this AP to channel 7 and works perfect