Use identical SSID, Security Protocol and Passphrase on all WAPs.
Set each WAP to a separate channel. Leave a two channel space between. (e.g. 1, 4, 7, 10, 13, 16)
In your coverage area, overlap your WAP signal radii. As your WiFi device moves through your area, it’ll lose signal from one WAP and seamlessly join the next WAP.
These are WAPs, not routers. DHCP is handled by my server!
Don’t use “WAP Extender” mode, unless you have no Ethernet for the distant WAP to use… it’ll half your bandwidth.
You can use “inSSIDer” software (free) if you would like to look for interfering signals. You don’t want anything else using the same channels you have chosen. They will compete for bandwidth. You can also study signal strength with inSSIDer.
Experience dictates… be careful about selecting the 5GHz band on Dual Band WAPs. Some devices (even brand new notebooks) do not see this Band. For compatibility, I end up using the more crowded 2.4GHz Band…