How do I change the name of my router? DLink España
How to Connect 2 Routers on the Same WiFi Network YouTube

@Joseph But it's not a repeater setup. The second router is not repeating the WiFi signal, it gets the connection from a hard wire. I've got the same setup at my house using Apple gear (routers that do expect you to do this, making it a bit easier), and it differs greatly from the former repeater that I did have setup. Google OpenID guy above describes setting up the spare router as a repeater.
How to change your WiFi name (SSID) and password on your router Sabai Technology

Here is a quick overview of what you should do to extend your home network with a second access point: To extend your home network: Connect two access points to the same network. Make sure that there is only 1 DHCP server. Use the same wireless network name (SSID) for both AP's. Use the same password and encryption settings for both AP's.
networking Dualband Routers with the same SSID? Super User

You may have 2 separate issues. Using the same SSID/passwd on different APs on different networks will cause client issues if they 'roam'. Normally when roaming AP just the wifi connection to the new ap is required - and initiated by the client. this keeps the status of the network connection in the device OS 'up' meaning that network connections stay 'alive' and no re=dhcp is.
How To Configure Mi WiFi As Second Router To Extend Existing NetworkSame SSID Roaming

Navigate to the wireless settings page and set up a unique SSID (network name) and password for your Wi-Fi network. This will be used by both routers. Make note of the wireless mode the router is currently set to (e.g., 2.4GHz or 5GHz). It should support the same mode as the secondary router you plan to connect.
A Quick Guide on SSID and Wireless Networking

Currently looking to set up a home network on a large house with multiple routers all on same said and password, the routers are all wired. From what I've already read the best thing to do it setup main router (router 1)on IP 192.168.1.1, router 2 on 192.168.1.2 with disabled dhcp. Same on router 3 with 192.168.1.3
How to Create Different/Separate WiFi password for each WiFi user or person Free Radius

Problem: There are two wifi networks I want to connect to regularly. But they have the same ssid. As far as I can tell, I have to reconfigure my wifi settings (passwords and authentication methods not the same) each time I move between them. I do not control either network, so cannot change their name.
Configuring two wireless routers with one SSID name) at home for free roaming Scott

nathanliefting (Larcorba) February 4, 2016, 7:25am 3. Give both APs the same network name (SSID), the same security type (WPA2-PSK recommended), and the same wireless security passphrase. Many clients assume that these kinds of settings will be the same across all APs with the same SSID. If you just set that up it will use the best AP around.
How to Add Multiple SSID in Single Access Point [Multiple WiFi Name]

12. Two identically named SSIDs with the same password will allow your device to connect to either, without having to add any extra networks on your devices. If both routers are broadcasting from the same location, the expected behaviour will vary depending on device. For example, some devices will connect to whichever router has the stronger.
Problem Connecting Multiple Wifi Routers With Same SSID

12. Power on your primary router. Now both routers are broadcasting the same SSID and allowing computers on the network to access each other and the Internet. The SSID, or Service Set Identifier.
Problem Connecting Multiple Wifi Routers With Same SSID

When your router has been reset, connect an ethernet cable to LAN 1 on the back of the router and the other end to the computer and turn the router on (if it isn't already on from the reset). Open a web browser on the computer and go to the default IP address of the router. This is usually 192.168..1 or 192.168.1.1.
3 ways to connect to hidden WiFi networks in Windows 10 Digital Citizen

Having them as you're describing, even with the same SSID and password, there is no guarantee that the devices will switch between the networks without user intervention (usually a device will have to be completely outside the range of a network it's connected to before attempting to connect to a different network) and even if the devices do.
Configuring two wireless routers with one SSID name) at home for free roaming Scott

LAN-to-WAN: Change the IP address to 192.168.1.51. Notice this is just outside of the DHCP range we set up on the primary router. Once the IP address is set, just make sure that the subnet mask matches that of the primary router and that you disable UPnP if the option is there. 5.
How to change SSID & Wifi Password?! YouTube

Mesh networks will repeat their SSID several times here, and your success may vary depending on which node you select. Step 2: List your networks and select the one you need. Step 4: Cracking.
How do I change the name of my router? DLink España

Make your life easier by changing the SSID and password on the new router to match your old router's SSID and password. When your Wi-Fi devices try to connect to your network, the first thing they do is look for a network that matches the SSID you previously told them to use. It won't know that the router hardware changed, just that the address.
192.168.18.1 192.168.1.1

WiFi Central Get Tips and Tools for Your Wireless Network

It is worth noting that these networks will not share their settings so you would need to configure both networks to use the same SSID, Password and Security settings. New Release - Kasa KS240: Smart Ceiling Fan Control and Dimmer Switch