To turn on a station manually, you need to switch the controller to manual mode first:
http://:8080/?pw=opendoor&mm=1
then
http://:8080/sn1=1&t=0
This is because directly turning on/off a station is implemented as part of the manual mode operation. If the controller is in program mode, it won’t accept such commands. At least this is how interval program 1.x is implemented.