I do not understand. what do you mean with many hosts 2016 and 2010? The host operating system is vSphere Esxi. Do you have virtual machines with Windows 2016 and Windows10 that have become slow and not connect in RDP?
I would start by saying that you are using an unsupported ESXi version and you should upgrade.
Do you have VMware tools installed and updated on those 2 vms? Did you checked nw,storage performance?