A popular claimed Sanskrit cognate (sarvara, an epithet of one of Yama's dogs) has been judged phonetically problematic by the standard modern academic authority on Greek etymology, Robert Beekes, who classifies the name Kerberos as Pre-Greek instead, meaning no successful derivation from any known Indo-European root has been established.
What would resolve this Either a securely attested Pre-Greek Aegean word the name can be shown to derive from, which would require new epigraphic or comparative evidence beyond what currently survives, or a phonologically sound Indo-European derivation succeeding where the Sanskrit-cognate proposal has failed.
OpenHistorical and comparative Indo-European linguistics, Pre-Greek substrate studiesRobert S. P. Beekes, with Lucien van Beek, Etymological Dictionary of Greek