I don't see how that would be a solution. All my USB input goes into a powered hub and from there to the USB3 ports on the NanoPi. Everything else continues to work fine, e.g. the ASI120 guide cam continues to feed images, FW stays connected as does the mount.
I would expect them to drop out as well, if the USB port cannot provide enough power and therefore drops the connection.

Why only the ASI1600MM?

I found this post on the ZWO forum talking about a similar issue on a Rock64. Looks like it may be a kernel problem

bbs.astronomy-imaging-camera.com/viewtop...f=29&t=8253&start=20

Unfortunately all the OS images for the M4 seem to be based on the 4.4 kernel (FriendlyDesktop, Armbian Buster and Armbian Bionic), I'm not sure how easy it is to update the kernel on Armbian

It definately looks like a kernel problem. I had a play with a dev version of Armbian Bionic that uses kernel 5.0.0 and the camera ran perfectly, at least for the quick testing I was able to do.

With the default 4.4 kernel I could only take 2 or 3 images before it would stop. With 5.0.0 it never stopped, I was even able to loop images and start the video streaming too.

Unfortunately the dev versions of Armbian don't include a desktop, I was able to install enough for testing Ekos but it wouldn't have been useful long term. I wonder whether it will be easier to try to install an updated v4 kernel into the existing desktop Armbian install, rather than trying to install a desktop into what looks like very much a beta dev branch running v5.

Cracked it!!

I built the dev branch of Armbian from source, installed that and it worked.
The camera works almost perfectly, occasionally I get a message, seemingly from the driver itself that it can't connect, but unplugging the camera and plugging it back in again fixes that every time, and then it runs fine after that.

The only problem with the OS that I've come across so far is that the WiFi driver appears to be missing. Wired networking is fine though.

Does anyone know what driver the WiFi uses on these boards?
Please could someone do an "lsmod" and find the WiFi driver name, as I can't find out what it's called without going back to an old installation.

If you do an lspci then you should be able to find out which WIFI card you have and you can search for the driver.

lspci returns nothing at all, I've never seen that before

Me neither! Weird...

The driver is rtl8xxxu.

Thanks, at least I know what to look for now

Hmm, I have the driver but when I try to install it manually it returns with "Unknown symbol".
It would have been compiled from source with the kernel, so I don't know why it won't load.

There is other weird stuff going on with these systems on the NanoPi-M4. I have been trying to activate X11VNC using a separate administrator account instead of the 'pi' user account on the system. For the life of me, I cannot get the startup script for calling up the VNC server executed, although it runs perfectly fine when I run it in the terminal. Adding it to the autostart folder in ~/.config doesn't help either. All the permissions for that folder should be set correctly. The very same script with the very same method executes and connects perfectly fine at startup when I log in and autostart it as user 'pi'.
Happens only on Lubuntu, though, not with the Ubuntu image.

Maybe you are encountering similar permission problems when you are compiling the kernel on those systems.

I don't think so, I built the OS by following the Armbian instructions. That uses a desktop Ubuntu 18.04 image to cross-compile for ARM.
I built it in a VirtualBox VM.

I had nighmares with VNC too, nothing I tried would work properly. I think I tried every single package available with VNC in the name.
In the end I got it got it working fairly easily using tigervnc-standalone-server and a systemd unit file to start the service