What sort of devices can the TL-SG1008P power?

It is intended for IEEE 802.3af or 802.3at PoE devices such as compatible wireless access points, IP cameras and IP telephones. The device still has to be within the available per-port and total PoE power limits.

Check the powered device's PoE standard and power requirement rather than assuming that any product with an Ethernet socket can be powered through it.