Picked up a nice TYT MD-390 UHF non-GPS for cheap a month or so back and I think I have it programmed correctly with the local repeaters/talk groups and it's running the md390toolz custom firmware, but I'm just a tad too far to talk to those repeaters so I grabbed one of those MMDVM hotspots, link below.  If programming the radio was any indication then I'm assuming programming the hotspot and making the two talk to each other is going to be a pain in the ass.

The MMDVM appears to be the same as all the other jumbospot clones and kits on ebay, all based off the Raspberry Pi zero.  Any owners on here that could point me in the right direction on getting this programmed and adjust my radio programming to work with the hotspot?  Or know of a good guide I could read or watch?  I don't have any specific talkgroups in mind, never used DMR before, so I figure I'd just listen in to a few popular TGs and the arfcom TG if it's still around.  Can I have TGs loaded from different DMR networks?

My hotspot - https://www.amazon.com/mmdvm-hotspot-Support-raspberry-Antenna/dp/B0779HC2NM/

Found this guide to go through the initial setup and I have the configuration page all filled out properly I think, and it's connected to my wireless in the house.  Now I just need to pick a frequency for it and start configuring all the DMR stuff, then get in to the radio's codeplug and do whatever is needed there to get it to talk to the hotspot.

I really hope DMR gets some much needed simplification updates.  It's a bit surprising how complicated all this is and that's coming from a network/system administrator.

ETA1:  On my TYT MD-390 I added a new digital contact(TGIF - Hotspot / Group Call / 556), added it to my RX Group member list, added it to the Zone member list, added it to the Scan member list, then under channel information I created a new channel(in addition to my existing local channels) with the following info but I'm not sure if it's correct;

Name: TGIF - Hotspot
TX/RX Freq: 433.300MHz
Admit Criteria: Color Code
Contact Name: TGIF - Hotspot
Color Code: 1
Repeater Slot: 2
In Call Criteria: Follow Admit Criteria
Power: Low (assuming this is my radio TX power and wanted it low since I'm sitting 5ft from the hotspot and don't need to blast it)

In Pi-star I have TGIF Network/1 set and 433.300MHz set as my frequency.

ETA2:  I have 556/ARFCOMM and 31665/TGIF in my radio(since it had active talkers which would help me test), listening in on a convo on the TGIF talkgroup right now.  Can't seem to figure out how to stop listening to one TG and start listening to another while a conversation is taking place on the one I'm currently connected to.  Once those fellas stopped talking I was able to switch to another TG from the radio.  Is this normal behavior?

ETA3: I'm sitting here thinking about how there are dual band DMR radios and in my area there are UHF and VHF DMR repeaters.  Is there any benefit at all to spending $200+ on a dual band capable DMR hotspot?  My understanding is that UHF or VHF are just the options you have to connect to the networks and their talkgroups, so if you have a dual band DMR HT and want a hotspot due to repeater distance or wanting to access TGs your repeaters dont host, you don't need to spend $250 or more on a dual band hotspot when a UHF hotspot will be sufficient.  Am I correct here?

I don't see a real need for a dual band hotspot, unless you live in an area that is saturated with other hams using 70cm hotspots. Given the fact that a typical hotspot has only 10mw RF output, interference from other users is highly unlikely. Your range is limited as the receiver on the typical MMDVM hotspot is poor. Hotspots were not designed to give you city wide coverage like a repeater. What I like about hotspots is that you are not dependent on a local repeater to get on DMR or other digital networks.

I program each DMR talk group into a separate channel on my radio. To disconnect from an active talk group you will need to program an unlink channel with TG4000. You then have to push your PTT momentarily to disconnect from the active talk group you are using.

Brandmeister requires you to do this if you only want to hear one talk group at a time. When I first started using Brandmeister, I found myself connected to multiple talk groups simultaneously until I learned that I needed to unlink with TG4000 prior to changing channels and talk groups.

You are correct, you can only disconnect from an active talk group when there is a break in the ongoing conversation. If your try and change talk groups while someone is still talking, keying up the TG4000 unlink will not work. If your are listening to a very active talk group like TGIF TG31665 you will find its almost impossible to get disconnected.

However when using the TGIF network, you can go to their online self dashboard and disconnect from the active talk group even while people talking.

TGIF self care

TGIF also allows you to change talk groups by changing channels without unlinking with TG4000  by simply pressing PTT when the channel is clear. It will automatically unlink you and  switch you to the new talk group. Again this only works when the talk group you are listening to is clear. I find it much easier to switch talk groups on TGIF than Brandmeister, as I don't have to use TG4000 to unlink.

On the Brandmeister network you will have to use the TG4000 to unlink or create a user account on their website and disconnect via their user self care page.

Brandmeister web page

Nice video tutorial on programming Pi-Star by N1MSG.

Pi-Star Setup

Finally the best written tutorial on Pi-Star is written by KE0FHS.

Playing with Pi-star

I figured out the 9900 and 4000 TGs for testing my audio and disconnecting from another active TG, and did find that self care page for DCing as well.

At this point I am pretty confident the radio and the hotspot are properly configured.  Now I just need to figure out what TGs I'd want to connect to.

On my MD-390 each TG has its own channel, or what the TYT CPS calls digital contacts.  The first six channels are the hosted TGs on two local-ish UHF DMR repeaters.  Everything after that is TGIF TGs, all with a prefix of TGIF- so I know what they are and that they're hotspot only since no repeaters in my area connect to TGIF.

One thing I can't figure out is when I connect to a TG I show up in the active talker list but as unknown callsign and unregistered name, though it does show my RadioID under the DMR ID column.  Does TGIF not pull callsign and name info from radioid.net where I applied for my ID?

ETA:  Also, what do I need to know about TXing and timeslots when it comes to DMR?  If I hear someone announce that they're monitoring, can I just reply or is there some sort of system here I need to follow?  I don't quite understand what the timeslots mean, if it's like FT8 or something where I have to wait for my turn/timeslot or etc.