Digitrax LNWI Mystery Solved (Updated 2022-08-30)

After much research plus trial and tribulation the author finally has Digitrax's LNWI WiFi interface figured out and working properly with our club layout. The Digitrax forum on groups.io has been alive with discussion on this hardware. Some of it correct and some not. Some close and some not so close. Here's what the author has figured out.

Key point 1:
    The LNWI channel number must match the duplex channel number 
    (minus 10) that the UR92 is set to.

    WARNING
        The UR92 supports duplex channel numbers 11 through 26 while
        the LNWI only supports channel numbers 11 through 21 
        (1 through 11). If the UR92 is programmed to any of the 
        channels 22 through 26, there is no guarantee the LNWI will
        function properly. Read as - Don't use it!! (or change the 
        UR92 channel number). Hopefully, Digitrax will fix this in 
        a future firmware upgrade

Key point 2:
    The Loconet group name must match between the UR92 and the LNWI.
    Since the LNWI itself has no way to program the group name, how 
    can this be done?

        a. With a throttle plugged into the UR92's front panel and the 
           LNWI plugged into loconet and both turned on, <UPDATE> make 
           a change to the group name and save it in OPT/EDIT mode on 
           the throttle press ENTER on the throttle. This will update 
           the LNWI to the group name of the UR92. No need to make any 
           change.
        <UPDATE>
           b. With power off to the UR92 and the LNWI plugged into it and
           powered on, power on the UR92. The LNWI will be told what 
           the group name and the channel number is.
           Powering up anything in any order makes no difference! It 
           does not force a UR-92 update.
        c. Use the DigiGroupSetup utility provided by Digitrax
           to set up the values. (I cannot get this to work I believe
           because my LocoBuffer-USB interface has a different baud rate
           than the utility supports. Please leave a comment if you 
           figure this out).  

Key Point 3:
         The 'network number' has nothing to do with the UR92. Set this
         via the LNWI's OpSw's as per the instructions. This changes the 
         LNWI's IP network number in case another model railroad club is
         using the same number as your club. It can be 0 through 7. (For 
         the techies it's the third octet in the IP address 192.168.7.1
         the 7 in this case)

Key Point 4
         How can I check what these values are set to on the LNWI to make
         sure they are correct? Simple!! Look at the connections page on 
         your phone (or android device or iPad). You'll see this:

             Dtx1-YYYYYYYY_XXXX-7
         
         Where

             Dtx     -> the Digitrax identifier (can't change this)
             1       -> the duplex channel number (my be different
                        depending on what you set the channel # to)
             YYYYYYY -> the 8 character loconet group name
             XXXX    -> the LNWI ID set by Digitrax (can't change this)
             7       -> the network number

Conclusion
If the channel number and group name displayed on your wifi device do not match what's programmed in the attached UR92 there is no guarantee the LNWI will work properly and it will probably corrupt what duplex throttles can acquire and control. The author has seen an improperly configured LNWI hijack a DT402 throttle and not allow it to control ANY locomotive. In this case the throttle will display the group name of the LNWI (which is totally useless to it) not the UR92.

The Digitrax knowledge base article on the LNWI (KB1053) is located here. As long as you follow the above setup instructions and your LNWI will update you shouldn't have any problems. Have fun.

<UPDATE>There may be a concern related to your throttle's firmware version. Throttles with v2.1 (Digitrax's latest) did not seem to have a problem. We were unable to check a throttle that was having a problem with an unsynced LNWI. For recent additional information on this see this post

<UPDATE>This author is a regular committer to both the JMRI and Digitrax forums. Lately on the Digitrax forum it has become apparent that several people have had problems with their LNWI absolutely refusing to sync up to their UR92 regardless of what they have tried and even after following the steps in this post. One of them sent their LNWI back to Digitrax for repair. They received the cryptic message "REPROGRAMMED CPU SHIPPED" whatever that means.

<UPDATE 2022-08-30>From Steve Long on the Digitrax groups.io forum:

There is a problem with an LNWI and a UR93 combination on layouts. The LNWI interferes with UT4D throttles acquiring a loco address.  It is not a problem with UT6D throttles.  The workaround for UT4D throttles is simply to disconnect the LNWI from the LocoNet for the few seconds it takes to acquire a new loco address on a UT4D.  The LNWI can then be reconnected to the LocoNet and both the UT4D and WiFi throttles can be used simultaneously to control trains on the layout.

The author could not verify this as he does not have a UT4D throttle. 

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