The MCS policy was set to "round robin".

Now, I do believe we are using the default Microsoft MPIO driver, but where can I check than on Windows and confirm? I do not remember where ...

Also, forgot to mention and I actually was not aware about this until yesterday, we do not have two switches but only one and both nodes are connected to same switch. That actually defeats part of MPIO purpose, I think. Not sure why our IT resource made it that way.