Note that 37017 is the port for mongo, which is not open outside of localhost. If you run testssl on 17017 from outside the local machine, you'll see it gives you the correct results:
SSLv2 not offered (OK)
SSLv3 not offered (OK)
TLS 1 not offered
TLS 1.1 not offered
TLS 1.2 offered (OK)
Note that 37017 is the port for mongo, which is not open outside of localhost. If you run testssl on 17017 from outside the local machine, you'll see it gives you the correct results:
SSLv2 not offered (OK)
SSLv3 not offered (OK)
TLS 1 not offered
TLS 1.1 not offered
TLS 1.2 offered (OK)
(etc)