To my knowledge, the version of VMM console should be identical with the VMM server. Please help check it.
Plus, please make sure that there is no firewall rules which may block the communication between VMM console and server. Please view the screenshot for the ports used for VMM console.
Finally, although there is no public doc introducing the os requirements for VMM console 2012 R2, by referring to doc for VMM 2016, it's not supported for installing VMM console on the later version, such as Windows server 2019. Please refer here.