Dear @AgrippaEPL,

The TL-SG1016PE V2 supports IEEE 802.3 af/at standard, please ensure that your PD(the WIFI terminal ZYXEL) is also based on IEEE802.3af/at first before you try the following troubleshooting.

1. Only the Port 1- Port 8 are PoE ports on the SG1016PE switch, ensure that you plug into the right port.
2. Check the cable you are using, qualified Cat.5 or above Ethernet cable and the length of the cable is not over 100m. 
3. Confirm the power supply mode with the PD’s vendor, there may be two situations that cause the problem:

• 1) The PD only supports Alternative B. TP-Link’s PoE switches are based on Alternative A. So the PD and PSE cannot cooperate together.
• 2) The PD supports Alternative A, and the line pair 1/2 is passive pole and the line pair 3/6 is positive pole. In this case, the PD cannot work if you use the straight-through cable, but you can use a crossover cable instead to avoid the problem.

So if the PoE LED does not lit up on the switch after you plug your PD into the PoE port and your PD can’t be powered on, it is recommended to contact your PD’s vendor and ask for the PD’s power supply mode and the polarities it supports after eliminating the basic network factors. This information is also necessary when you contact TP-Link support.

Here is an article for your reference. https://www.tp-link.com/support/faq/1003/