it seems the drive might have issues, it would read not very many media; some cd it would read, but with dvd now had less luck;
could also be due to the aftermarket  ac/adapter that had to buy;

https://ibb.co/yMBHbJN
https://ibb.co/Z6p6N1bH

No!
Iso file systems are readable on any OS. At least should be.

Consider using an OEM written media to test the drive.

what do you mean by that? like an audio CD that came from a Musicshop? or a Film - DVD?

no, no dmesg , but had checked previously , and the drive figured among the long listing.

now mac is back to mac os x; will check another time with a live-session.

EDIT: if on mac it says "unreadable", there is high chance it is "readable" but contains a linux session or similar, that for mac is just not "readable" out of the box, but still perfectly readable for the drive itself.

Not the right media to use for a test unless you are absolutely certain than you can read it in any other drive.

Consider using an OEM written media to test the drive.

Have you checked the dmesg printouts?

A.

on the mac side it reads it, or better, recognizes it as "not readable".

https://ibb.co/DD05GGB3

From the linked screen capture, it would seem that the hardware is working.

Just in case, boot the box without the optical drive plugged in, plug it in and check the dmesg printout.
If the drive is correctly recognised by the system and no errors are reported, it would mean that it is not a Devuan issue.

If the drive is working properly, the problem would lie either with the media or with the laser optic itself.
Check with a known/working factory stamped (readable) CR-ROM or DVD to rule out the media being bad.

Q: can you hear the drive spin when you load a DC/DVD? What does the dmesg printout say?

If the problem is the laser optic, it may come down to something as simple as a dirty lens or a more complicated issue like eg: a damaged laser assembly or a power problem*.

A properly working drive should recognise the media it was designed for.

Check here for the manual and specs for that drive (SH-S162L?).
https://samsung.manymanuals.com/optical … nual-14158    <- see page #32 of the manual

Best,

A.

* From a a fast look at the manual, it would seem that the drive is an internal ATA/ATAPI (E-IDE) model (?). ie: needs both 12v and 5v power.

It could be that whatever adapter you are using is not providing enough power for the laser to read properly.

https://ibb.co/h1446ZgK

have installed Devuan 5.0 on an older Mac and attached an even older optical DVD Drive (Lightscribe-enabled) via Firewire 800/400 Adapter and cable;

The drive is not being recognized eg. not shown in File Manager when i insert optical media;

Can someone please help to debug the issue;

Have read somewhere that firewire is supposedly still being actively maintained for some time;

Thanks.