OK, let's see if I can help explain stuff for you. When W1MSG made the videos (the DMRGateway configuration videos show TG 7 and how he was changing rooms - I do not know).
As far as I have experienced here is how DMRGateway 'routes' the varios networks (up to 4 but a caveat -- later)
Your Brandmeister (normal operations all Talkgroups use the 'straight numbers (choose your BM Master first -- I am in USA so I use Brandmeister 3101)
Brandmeister has reflectors too -- for these you need TG 9 but Private calls to the different reflectors (4001 -> 4999) * a PC (private call) to 4000 disconnects the reflector (not the TG (talk Group) ) which is a GC (Group Call) to disconnect from a TG) a PC to 5000 plays the current reflector [A FEMALE Voice]
DMR+ uses Reflectors ONLY on TG 8 but to change a reflector for the DMR Network you prefix an 8 onto it so they look like 84001 -> 84999) if you are on TG 8 as with DMR+ you should be, you will hear a MALE voice -- the 4000 disconnect and 5000 Status numbers do not work in DMR+ but, you can Jerryrig it using the DMR+ Options Line so it looks like the following:
what this translates to is: you start DMR+ not linked to any reflector (effectively disconnected) -- want to start on a certain reflector always change the 4000 to the reflector number, but be carefule the next part will revert to this reflector as a 'static return' spot
If you do not transmit for 60 minutes or more, whatever reflector you WERE on reverts to StartRef reflector (so 4000 would disconnect you from whatever you were on when the hour mark of no transmit was reached.
The UserLink set to 1 allows you to change reflectors on the fly and the TS1_1=9 is to tell DMR+ that TG9 stuff on DMR+ should be put on TG8 (as to how, not sure but it does so don't mess with this)
Now for XLX -- this uses TG6, but this is a bit weird ad XLX has Reflectors and Modlues -- I'm about to blow your mind a bit. -- you don't have to use XLX if you don't want to.
So XLX reflectors -- to change these you PC (again Private Call) to 68XXX where XLX is its reflector number i.e. 68307 will put you on XLX307 or 68950 will put you on XLX 950 (voice says [Female] Connected to XLX 307 D)
OK, where the he// did the D come from? that is the Module I spoke of -- you can change these too.
These are done by a PC to 64001 -> 44026 as : 4001=A, 4002=B 4003=C...4026=Z so A->Z=4001->4026. Don't worry it takes time.
OK now for the NEW stuff, the DMR2YSF and DMR2NXDN -- this is a CAVEAT only one or the other NOT BOTH at the same time, they both use TG 7 but with a difference -- DMR2YSF you are stuck in the room in configuration where in DMR2NXDN youCAN change rooms.
DMR2YSF use 7 straight and set your configuration in the Pi-Star web interface. I have not heard if that limitation is fixed yet.
DMR2NXDN on the other hand you prefix the NXDN number with a 7 but pad it to 5 digits so i ends up as 6 digits, pistar.us (this main site) has a list of the rooms in NXDN Tools section) but note the Florida 'node is 1200 (only 4 digits --it needs 5) so this would be entered as GC to 701200 and you stay on 701200 it's not like you set to 701200 and then talk on TG 7.
I hope I confused you enough but go back and watch W1MSG's stuff with a little of this in hand (he explains the software end but to demonstrate on the common radios, well that don't happen often. I may have to do a few -- only have DMR on Anytone 868 and an MD-380. but if people want to throw me a Yeasu or DStar capable radio - I won't object
So to recap a bit:
Brandmeister uses the BM Talkgroups you are used to (or go to brandmeister and see the ginourmos list of options) but their Reflectors use TG 9 and a Private call to the reflector number.
DMR+ uses TG8 and to change reflectors here -- prefix it with an 8 ** if you don't you actually are changing the refletors on Brandmeister with some wacky results.
XLX uses TG 6 and XLX masters can be changed with Prefix of 68+XLX number -- Modules are 64001->64026 (A->Z) -- Many XLX reflectors point to BM talkgroups or have other points to access them without XLX on.
YSF and NXDN crossModes are one otr the other at a time - you cannot do both at once -- uses TG 7 or a 7prefix for NXDN)
Further reading is here: https://www.toshen.com/ke0fhs/pi-star.htm
-- there is a LOT of info, take your time KE0FHS, Toshen does a really good job.
Also explore the tools on pistar.uk as this has a wealth of information too.
Come back and ask what you need (my contact info is in my profile) -- I am no expert, don't claim to be, don't rewally ever see myself that way, I just help where and how I can.
Good luck and have fun -- we are all new at somethng sometime.