I am getting an SSID conflict and need to know how to separate 2.4 and 5G.

You don't. 

There used to be a method using telnet but reboots/firmware upgrades would break it. 

And I think its been blocked by firmware upgrades. 

What actual issue (in detail) are you having? I've been running mesh systems for years (with multiple companies) and haven't found a device yet that I coudln't get to connect.