The latest QNAP NAS firmware update has made SMBv1 incompatible with older camera models in the 4 and 5 series. This is due to known security vulnerabilities in SMBv1, which can expose devices to malicious attacks. QNAP recommends updating to newer SMB versions and implementing additional security measures to keep devices and data safe.
I too have a client using a TS419P II and the same happened to the M15 and D15 on their system. I have been working with QNAP for a couple of months now to get a resolve.
I have tried reverting back to previous software where the SMB-1 was functioning, but again that has failed.
Hopefully someone from Mobotix can address this issue as all I have got from there technical so far is that the older cameras only run SMB-1.
Unfortunately, like yourself and no doubt many others around the world have been let down by both companies.
Certainly questions the use of QNAP (unfortunately we run a good few of them)