SSL/TLS issue connecting to Amazon

We are unable to manage EC2 instances from Foreman, receiving the following error.
Excon::Errors::SocketError: SSL_connect returned=1 errno=0 state=SSLv2/v3 read server hello A: unknown protocol (OpenSSL::SSL::SSLError)

Expected outcome:
Working ability to contact EC2 and provision hosts etc

Foreman and Proxy versions:
Foreman: 1.10.4
Foreman Proxy: 1.10.4
Foreman and Proxy plugin versions:

Other relevant data:
We have what we believed to be an identical foreman install that works perfectly as expected. Configuration appears to be the same, and so are the Foreman versions and the OpenSSL versions.

We are behind a proxy, but this proxy is identical on the working/non working host.

I appreciate any support

maybe a time drift? clocks should be in sync.

Sadly not, looks to be the correct time

Based on the error I would assume something is forcing the connection to SSL3, whereas AWS only support TLS.