Why doesn't mount.cifs mount some resources?

Question

linux

After updating cifs-utils to 6.7 (or maybe updating the bucket - now 4.14.19), for some reason the balls from one of the windows servers stopped mounting. Windows 2012 stands there, configured for a long time and very crooked, but it used to be mounted.
Now when I enter the command:

# /bin/mount -t cifs //serv/share /home/user/share -o credentials=/home/user/credstore/credstore.txt,uid=1000,gid=1001,rw,nocase,file_mode=0644,sec=ntlmssp
mount error(5): Input/output error
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

If sec is replaced by ntlm or not specified, then it generally gives out:

mount error(22): Invalid argument
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)