So far I had manually started indiserver on my small PC at the mount, and then used EKOS on my laptop to connect to it:
Today I wanted to check if the computer is powerfull enough to also run kstars/ekos on it, and wanted to make use of ekos starting indiserver by itself. For that I had to select a mount (CEM60). This created a new configuration in ~/.indi, named iOptron CEM60_config.xml. The other one, created when running the manual indiserver command, was called iEQ_config.xml. And of course, after that change, PHD2 didn't find the mount anymore, as it was looking for the iEQ device
So I checked the running indi programs, but that didn't give a hint how the name had been passed to the indi_ieq_telescope program. I'd really like to use the same name for both methods so I can easily switch without having to change the configuration of PHD2. I tried 'indiserver --help' but that doesn't mention driver options...

How would I have to start indiserver to use the new device configuration file?

With EKos and INDI both running on your small remote machine, where is PHD2 running?

That's also on the PN40. The Gemini Lake Celerons are quite powerful...

It's not the default configuration, usually I have it doing only INDI and PHD2, and connect from EKOS running on my laptop which then also does plate solving and storage. But as that has the inherent danger that things stop when the network is down I'd like to have a fallback running everything there via an x11vnc session.

I've currently switched to also manually start indiserver when running EKOS on the PN40 and connect 'remotely' to localhost. Then I get the iEQ config, just like when connecting from the laptop.

But I'd still like to know how EKOS starts indiserver/indi_ieq_telescope to use a different config name/file

Terminology might be different but when operating locally you use the driver name and when
indi is remote from Ekos use the display/label name. In the Ekos profile hovering on the name will show you both. I think they are also shown if you use -vv switch when running adminserver.

If you start INDI Server in FIFO mode, you can start drivers with specific names (see indilib.org/develop/developer-manual/92-indi-server.html). Ekos always uses FIFO mode so that it can dynamically start/stop drivers and renames the default name (e.g. iEQ) to a more friendly label (e.g. "iOptron CEM60").

If you don't want to use Ekos and have INDI Web Manager installed and running, you can make an web API call and it would a profile with all the "correct" labels always.

Thanks Jasem!
I had not looked into developer info, but that indeed explains things very well