Lk2819,   As far as I can see there are no known issues regarding 6.7.1.9. The tech notes for 6.7.1.9., which can be found on page 21 here, show nothing listed for that firmware version.    Let me know if this helps.  
Hi,   Where can we find the known issues list of DNOS 6.7.1.9?    Thanks in advance!    Lex
Known issues DNOS 6.7.1.9