X3000 name resolving

I am running docker containers within my network with each container having its own static IP address and a port number.
Example> container 1 would be IP address “1.2.3.4:5678” and name would be “math.mydomain.org
The IP address is madeup for illustration and is internal to my local LAN.
I access these docker containers using a web interface where i type in
http://1.2.3.4:5678
Instead, i would like to type in http://math.mydomain.org
How to do this?
I also have Adguard Home running

I have a lot of containers so it is easier to reach them by name.

I used to do this using HAProxy inside of Pfsense and it worked great.
I don’t know if HAproxy is supported in X3000.
If so, could i bring in the HAproxy config file in X3000 running HAproxy?

If not HAproxy, is there another proxy or something else to do this?

Since you are running AdGuard Home you can simply create an domain overwrite. DNS filtering rules syntax | AdGuard DNS Knowledge Base

I am not sure, if this will address the port number
My apps (docker containers) needs to be accessed as :
app1> https://10.11.12.13:8765
app2> https://10.11.12.14:9982
etc

Port numbers are not a DNS task.
You would need some reverse proxy if you want to omit the ports.

where is the reverse proxy section in GL.inet software?
If not there, which package may in install from openwrt ?

There isn’t an reverse proxy within GL devices.
You could use the preinstalled nginx and modify configs, but this would be completely up to you then.