OK, this helps a little. I am still working my way through the fog bank since I have no experience with or much knowledge about APRS (disclaimer). Let me just say that I work very deep in supercomputing and have pretty good knowledge and familiarity of operating systems internals (UNIX/Linux) and the full OSI network stack (layer 7 application up to layer 1 physical). I am a total newbie when it comes to ham radio topics. (more disclaimer).
First key is Brandmeister DMR. See:
https://wiki.brandmeister.network/index.php/Main_Page "We are a decentralized network active in 43 countries running a total of 57 Master servers."
I'm guessing that Brandmeister DMR is "the standard" used for the network stack implementation, sort of like TCP/IP is for the Internet. The terminology used in the wiki seems like it uses TCP/IP protocols for routing, connections and other networking concepts. It includes a server component and a client component.
More details here:
What is BrandMeister?
What is BrandMeister?
BrandMaster/BrandMeister is an operating software for Master servers participating in a worldwide infrastructure network of amateur radio digital voice systems.
If you are an amateur radio operator working in digital voice modes like D-Star, DMR, C4FM, APCO P25 or others (not all are supported yet!!). You do not need to know much about BrandMeister, and it's very easy to operate on its infrastructure.
If you are an amateur radio operator that runs a repeater in your local area, you may be interested in learning some more about BrandMeister and how you can take part in it.
A brief overview of BrandMeister core features:
Switching system for IP-enabled conventional Tier-2 DMR radio
Supports the most known network-access and end-user equipment making it easily expandable
Performs switching on the Layer 3 (Call Control) of the DMR stack
Has an embedded data stack (Layer 4)
Has embedded data and voice applications
Flexible routing based on data stored in a global database, local memory cache, and Lua scripts
Event notification using messaging queues (calls, connections, alarms, messages, locations and telemetry)
Implements mesh-topology for inter-node communications
They keyword is "switching system" which in this context probably means protocols put in place to maintain order when traffic moves through the network.
I'll be studying this further to decode how this all fits together but it seems like this has been adopted as the "standard" for these various digital modes listed.
This appears to be an all-volunteer open source type effort. It is difficult to discern with certainty about this but they are soliciting for volunteers and donations to buy H/W for implementation purposes. My kind of project.
The first thing I would check is the firmware.
The wiki page is here:
https://wiki.brandmeister.network/index.php/Chinese_radios and the entry for the radio is here:
https://wiki.brandmeister.network/index.php/AnyTone/D878UVIs the firmware at 1.10? If that checks out then we can assume the client (HT) software is current.
Also, check out the bottom of the page for the AnyTone. This terminology in ham radio context is a little fuzzy for me. Verify that features required are there or what the workaround might be.