This might make your task easier

^EDLIST("DIAG", "X123")=" internal health"
^EDLIST("DIAG", "X234")=" External health"
. . . 

So you will need this Function / Method to Update your segment:
The class is just a container for the method

Class ED.Update [abstract] {
/// assumption you have the full Segment already in a string
ClassMethod AddDescription(ByRef segment as %String) as %Boolean
{  set code=$piece(segment,"^")
   if $data(^EDLIST("DIAG",code),value)#10 set $piece(segment,"^",2)=value
        quit $test }
}

now all you have to do

/// ...  get the segment from DG1
    if  ##class(ED.Update).AddDescription(.segment)  {
          /// .....Update the segment in DG1
   }

If the code is not defined you just skip the update

With pure routines, this is an almost impossible attempt.
Since DO doesn't  have a differentiator between calling a function or procedure, internal or public or just looping  [ do {}  while ]

If you do it inside a class you have all this information on functions and procedures in %Dictionary.*
So you can define exactly what you search. And using the code generator you may even do it at compile time.

The most simple way  is to redirect your I/O to a TCPport where another job provides you with the expected input:
#1) have a listener:  (any port, I use 7777 for the example)

set listen="|TCP|7777"
open listen:(:7777):0  if '$test write "port busy",! quit
use listen read request
while request'="/*  your end condition */" {
    /* match request for correct reply */
    write reply,!

        }
close listen
     

#2) at your report side all you have to do is

set server =  "|TCP|7777"
open server:("127.0.0.1":7777):0
if '$test write "port busy",! /* termination sequence */ quit
use server

/* launch your program */

here the listener sits on the same machine but it could be any reachable IP-address.
the only critical point is if your program fiddles around changing $IO

 

it is not possible within the same class as you break the uniqueness of names.

But if you have class A1 with Method MX(....)  
you can create class A2 Extends A1 and overload Method MX as you like or need.
You still can call MX of class A1 from class A2 using ##super()

All with the assumption that neither class A1 nor Method MX is FINAL

Exactly!

here is the example Defining a JDBC Connection URL

   jdbc:IRIS://<host>:<port>/<namespace>

where the parameters are defined as follows:

  • host — IP address or Fully Qualified Domain Name (FQDN). For example, both 127.0.0.1 and localhost indicate the local machine.
  • port — TCP port number on which the InterSystems IRIS SuperServer is listening. The default is 51773 (or the first available number higher than that if more than one instance of InterSystems IRIS is installed — see DefaultPort in the Configuration Parameter File Reference).
  • namespace — InterSystems IRIS namespace to be accessed.

AHH! that sounds quite different.

First is your super server port really 53773 ?
Default is 51773.  While 53773 might be a gateway port for reverse connection. 
you can check in SMP  System > Configuration > Memory and Startup  

Otherwise 
I suspect telnet as a protocol might be blocked by some firewall by principle.
from a terminal prompt in IRIS  you might try this:

USER>set tcp="|TCP|7000"
USER>open tcp:(:7000) use tcp read req#15

So you create a TCP listener on port 7000 hanging around
Then try to connect from an external server by telnet to port 7000 on your server 
As soon as you send 15 or more characters the READ will complete and you see the content in variable req  

As you describe I assume this will fail. Indicating that some firewalls or similar blocks access.
Most likely the port is blocked.

In addition netstat -a from system prompt

or user>$netstat -a  from IRIS terminal  shows ALL listeners on your system

It's not clear to me what you try:

"..so customers can connect to IRIS remotely using JDBC and not ODBC...."

So they need the related Java-Libraries to connect.   see Establishing JDBC Connections

While the setting in your jpg. relate to the SQL-JDBC Gateway that allows access to other DBs over JDBC.
You have also a JAVA gateway to run java out of IRIS See Using the Java Gateway.