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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...
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Shyy's avatar
Shyy
Icon for Cirrus rankCirrus
Dec 22, 2025

I don't think it's an SNI error to be honest.

I'd make sure the client and server both use same TLS version.
also for debug purposes I suggest to use the default serverssl profile in the big-ip.
in the TCPDUMP just look at the TLS version and cipher suites.