Right. So… As you already discovered, there is no MMP method to set the RTC (real time clock) on the EPIC (or RIO).
Since they use Linux as their core OS and since it has NTP built in from the ground up we chose to go with that method of time synchronization.
The SNAP-PAC controllers did not initially have any NTP commands so we had to provide other methods for them to be able to adjust their time (like the time sync button in PAC Terminal for example). The PAC Control SNTP commands came much latter in their life, but now that we have them, its much easier to use them.
Via groov Manage you can configure a local NTP server if your EPIC (or RIO) does not have a gateway access to the Internet to sync its time.
The same local NTP server can also be used with the SNAP controllers via the SNTP server ULR string, so they don’t need Internet access either.
All that said, if you still want to use .Net to set both SNAP and EPIC controller RTC then you will need to use MMP for SNAP and .Net procedure call for EPIC.
Here is an example I found the web for the latter; https://stackoverflow.com/questions/54109936/how-can-change-system-date-time-in-ubuntu-os-with-net-core
I have not tested it and was just one of many such examples I found. (I chose this one because EPIC Linux is sort of close to Ubuntu).