The default cipher suite used by WM is very limited, especially lacking the ones for TLS. The failure you are seeing is because both system can’t find a common cipher, I believe.
You can check if 7.1.3 has this server extended setting:
watt.net.ssl.client.cipherSuiteList
(I use it successfully in 8.0.1 & later)
If yes, you can try to use this setting value:
watt.net.ssl.client.cipherSuiteList=TLS_RSA_WITH_AES_256_CBC_SHA,SSL_RSA_WITH_3DES_EDE_CBC_SHA,SSL_RSA_WITH_RC4_128_SHA,TLS_RSA_WITH_AES_128_CBC_SHA,SSL_RSA_WITH_RC4_128_MD5,SSL_RSA_WITH_DES_CBC_SHA,SSL_RSA_EXPORT1024_WITH_DES_CBC_SHA,SSL_RSA_EXPORT1024_WITH_RC4_56_SHA,SSL_RSA_EXPORT_WITH_DES40_CBC_SHA,SSL_RSA_EXPORT_WITH_RC4_40_MD5,SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5,TLS_RSA_WITH_RC4_128_SHA,TLS_DH_DSS_WITH_AES_128_CBC_SHA,TLS_DH_RSA_WITH_AES_128_CBC_SHA,TLS_DHE_DSS_WITH_AES_128_CBC_SHA,TLS_DHE_RSA_WITH_AES_128_CBC_SHA,TLS_DH_anon_WITH_AES_128_CBC_SHA,TLS_DH_DSS_WITH_AES_256_CBC_SHA,TLS_DH_RSA_WITH_AES_256_CBC_SHA,TLS_DHE_DSS_WITH_AES_256_CBC_SHA,TLS_DHE_RSA_WITH_AES_256_CBC_SHA,TLS_DH_anon_WITH_AES_256_CBC_SHA,SSL_RSA_WITH_IDEA_CBC_SHA,SSL_DH_DSS_EXPORT_WITH_DES40_CBC_SHA,SSL_DH_DSS_WITH_DES_CBC_SHA,SSL_DH_DSS_WITH_3DES_EDE_CBC_SHA,SSL_DH_RSA_EXPORT_WITH_DES40_CBC_SHA,SSL_DH_RSA_WITH_DES_CBC_SHA,SSL_DH_RSA_WITH_3DES_EDE_CBC_SHA,SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA,SSL_DHE_DSS_WITH_DES_CBC_SHA,SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA,SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA,SSL_DHE_RSA_WITH_DES_CBC_SHA,SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA,SSL_DH_anon_EXPORT_WITH_RC4_40_MD5,SSL_DH_anon_WITH_RC4_128_MD5,SSL_DH_anon_WITH_DES_CBC_SHA,SSL_DH_anon_WITH_3DES_EDE_CBC_SHA,SSL_RSA_WITH_NULL_MD5,SSL_RSA_WITH_NULL_SHA,TLS_EMPTY_RENEGOTIATION_INFO_SCSV
#Integration-Server-and-ESB#webMethods#B2B-Integration