This does work well - I've used with many 1000/1200/1500 - but haven't touched for almost 10 years. Are you trying to do between 2 x 1500, or via a PC/server and Ethernet to the ulgx 1500?
Don't try the DF1/HD, as that is hit or miss. The FD should work fine.
The most common issue I saw with people failing is trying too hard - setting too many things which don't need setting. You will need to use the correct IP plus subnet mask plus gateway IP in the DOIAP. Also be mindful of the station id used by the 2 mlgx - both cannot be the default of 1.