The wake by signal feature is about monitoring the voltage of I/O port when the IFP is in standby mode. The IFP will turn on automatically when it detects the signal port voltage from low(0v) to high(5v).
As an example, the MacBook or Dell's HDMI cable is sending 5V to the monitor even when it’s asleep. Since the IFP doesn’t detect any variation in voltage (0v > 5v), the monitor will remain on standby mode.
Since this is a hardware related limitation on the IFP, the behavior won’t be the same as your regular monitor. However, there are some things which may help resolve the issue:
1. Try to adjust the sleep mode to S3 or S4 on the PC.
2. Remove the HDMI cable from the PC after turning the IFP on standby mode.