[chris_f]

I had a similar problem connecting a UR3e:

-Universal Robots UR3e, Polyscope 5.4x? (as delivered in December 2019)
-Set IP address on PC to 192.168.1.1, subnet mask to 255.255.255.0
-Set UR3e robot IP address to 192.168.1.2
-Windows 10 Firewall: turned OFF
-CAT6 cable from UR controller to PC
平test: successful
-Connect: waiting . . . (never connects, no timeout or other indication to the user - something RoboDK could improve)

SOLUTION: (what worked for me):

-Installed Ethernet switch with another CAT6 cable between the PC and the UR Controller
-Connect: . . . waiting . . . (~ 0.5 sec delay) . . . CONNECTED!

Notes:

-You could also try a router; an ethernet crossover cable might work too
-I did NOT make any changes to the /RoboDK-Drivers/apiur.exe.ini file