This permanent fix works:

Found this solution for a different brand KVM and it worked for Dell's stupid KVM. Edit the Java.security file found \Program Files (x86)\Java\jre1.8.0_65\lib\security (for Win clients. There's a similar file on Mac/Linux elsewhere).

Looks like java new default is rejects key sizes less than 768. remove this setting and you can get into the KVM's.

Remark out the first line (already #), replace with second line.

# jdk.tls.disabledAlgorithms=SSLv3, RC4, DH keySize < 768
jdk.tls.disabledAlgorithms=SSLv3, RC4