When I 1st got my diseqc switches (4x1), I had them in the house, so I could conveniently connect my C-band, with old wiring/cables, in with my new (at the time) 80cm ku dish system. I had port "1" on C-band, port "2" on ku-band (BUD), and port 3 on my ku motorized dish, with nothing on port 4. It worked quite well. Then I got the Invacom Quad QPH031 LNBF to replace my Coolsat LNBF, that came with my ku system. I had to run a new co-ax line for the Circular side of the new lnbf. I hooked the Linear to port 3 and the Circular to port 4. The problem I encountered was, if I went to a Circular satellite, it would go there just fine. But, when I wanted to go somewhere from the Circular satellite, it would not move. I thought that something was wrong with my receiver? It took my lame butt a while to figure out, that the Circular satellites wasn't getting any diseqc commands to the motor, because the co-ax cable was going from the receiver to the diseqc switch to the lnbf, so it wasn't reaching the motor, to tell it to do anything. For the Linear side it worked fine. The co-ax went from the receiver to the diseqc switch to the motor to the lnbf, with no problems. Once I figured out what was going on, I put my diseqc switches between the motor and the lnbf's, and no more problems.
So, Yes it will work from the port the motor is connected to, but not the other ports not going to the motor, if you put the diseqc switch between the receiver and the motor.
So therefore, it's better to put the diseqc switch between the motor and the lnbf's, so all the ports will work. I hope this helps you understand?
Al