On the DA and each DC, edit the following file
$KARAF/etc/org.apache.karaf.shell.cfg
Add this line:
ciphers=aes256-ctr,aes128-ctr
Now re-scan and validate.
Note : These changes will be done by upgrade in 21.2.2 & the ciphers=aes256-ctr,aes192-ctr,aes128-ctr will be updated.