I'm looking at doing the same thing. According to Kerlink's manual, the barrel jack is 2.5mm x 5.5mm. This injector should work and it uses your original power adapter on the supply end. https://fiz-tech.net/products/poe-splitter-kerlink-barrel-jack-10-100-passive or on Amazon: https://www.amazon.com/gp/product/B07NP4TXSH/ref=ppx\_yo\_dt\_b\_asin\_title\_o00\_s00?ie=UTF8&psc=1