In the VMware vSphere Client, when I try to connect the CD / DVD drive, it hangs and it stuck on “Connecting”. To fix this and stop the CD / DVD drive being stuck connecting, I closed all VMware vSphere Client windows I had open. When I opened the vSphere Client again, it was no longer stuck connecting.
In my case, it was stuck connecting because I was trying to mount an ISO image from a “local” file, that was stored on another computer. I was accessing the ISO file from an admin share (C$), which I think the VMware vSphere Client didn’t like, I suspect it was hanging waiting for me to enter credentials but didn’t give me the opportunity to. Copying the file to the local machine that I was running the vSphere Client from allowed me to mount the DC / DVD drive and prevented it from getting stuck again.