I am using IDX of 6.4 and UF of 7.2.
However, I can not communicate from client hello to x.
An S in a cell indicates that this version of forwarder can send data to this version of indexer after you change the Secure Sockets Layer (SSL)/Transport Layer Security (TLS) version and cipher suite on the forwarder. See Known Issues in the Splunk Enterprise Release Notes for instructions on changing the SSL/TLS version and cipher suite.
I do not understand what settings I should add to UF.
Please teach me
With Version 6.6.0 they made fixes on the ssl handling. You have to tweak the settings on the UF so that it uses an "insecure" Version of SSL/TLS.
Another possibility is to upgrade the IDX to at least 6.6.