I recently changed from OMV4 to OMV6 when I saw that OMV5 was about to reach end-of-life. I had the same issue with being unable to connect from an XP 'live' CD running Acronis True Image when trying to image my XP machine. Adding the line: server min protocol=NT1 into the SMB/CIFS Extra Options allowed to connect again but, sadly, the peformance is abominable. Every other hardware/software component is exactly the same as it was with OMV4 but now it takes 8-12 times longer to save a partition than it did then. Using FTP also works but it splits archives into 2GB chunks leaving me with lots of separate files.
Are there any performance tweaks to make imaging work as well as it did before?