After you explored my RPi, I tried different combo with the D810A and saw different behaviors from each. I got another microSD card, on which installed the latest Ubuntu Mate for RPi and the indi-full and kstars-bleeding packages as well as the tightvncserver.
1. indiserver on RPi and kstars on Mac
In contrast to the case of the raspbian where I saw the Indi control panel, even the driver seemed not to start and showed the dialog attached.
I found 2 different logs, which are attached (remote_log_D810A_1.txt and remote_log_D810A_2.txt)
2. indiserver and kstars on RPI
In this case, gphoto started but could not recognize D810A. (see local_RPi_log_D810A.txt)
Is the gphoto2 contained the repository older than 2.5.9? (D810A is supported in ver. >= 2.5.9.)
3. kstars 2.7.6 on Mac
Does not work for any my Nikon DSLR as before. (local_Mac_log_D800E.txt)
I think we should have an updated INDI for Mac release that should fix the GPhoto2 library linking issue soon. For the previous issue, it was an odd somewhat complex issue that occurs when loading properties at startup. Anyway, one way to _test_ this is to disable automatic load of configuration. In KStars, go to Ekos option and set "Load Device Configuration" to Never. Afterwards, try connecting to your Nikon on RPI3 and see if that makes any difference.
Thanks, Jasem.
I did the test following your advise, start INDI with the Ekos option "Load Device Configuration" being "Never".
The D800E works fine in this case and the config can be successfully loaded pushing Load in the INDI control panel. Then stopped the INDI, connected D810A in place of D800E, and started INDI. The control panel appeared and I pushed "Save" the config, and got the yellow as before. After that, any pushing button did not do anything even Disconnect. In the .indi directory on RPI3, there is the config file "Nikon DSLR DSC D810A_config.xml", which seems so natual. After quit and restart the kstars, both D800E and D810A cannot be connected.
I checked on the RPi3 by lsusb and gphoto2 --status that both the cameras are recognized by the RPi3.
Then I rebooted it and started the kstars on Mac. First, I connected the D800E and got the first log. Then stop the INDI and connect the D810A, then start the INDI again. The control panel appeared as before, and I pushed "Load" config and got the yellow again.
After that, all the behaviors are the same. Then I again connected the D800E and restarted the kstars and INDI to get the third log which shows faulty to connect the camera.
The loading config after start of the INDI gave no improvement. I'll have to wait you solve this problem.