RB450 and RB750 in switch mode but not passing RDP over LAN

Hi everyone,
I have goggled for the last few days about port forwarding and having the routerboards in switch mode but RDP from one PC to another on a local LAN doesnt work. Cabling the two PC’s together via a standard switch works perfectly but not when going through the routerboards. All info I have come across talks about port forwarding from WAN to LAN , not 2 PC’s on the same LAN

I have set the RB’s to default that is supposed to put ethernet ports 2 to 5 in switch mode , can ping other PC’s on network and PC’s come up in “my network connections” but its like port 3389 is getting blocked somehow.

Any help would be appreciated
Scotty