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Forum Discussion

getrajan1's avatar
getrajan1
Icon for Nimbostratus rankNimbostratus
Dec 21, 2025

TLS handshake failure from BIG-IP to backend – Fatal Alert: Decode Error (Server SSL)

  Hello DevCentral Team, I am troubleshooting a server-side TLS issue where BIG-IP intermittently fails to establish a TLS connection to a backend service. Observed behavior: Client to BIG-IP TLS...
application delivery
neeeewbie's avatar
neeeewbie
Icon for MVP rankMVP
Dec 23, 2025

First, check whether server-side communication is working by using the curl command on the F5 device.
Also, since the TLS version may differ, allow all ciphers via the cipher group and perform a test.