Hey Julian,
the one you found it obviously for 12 V. But you need a triggering voltage of 3.3 V to connect it to the Onefinity controller.
If you want to switch a router like this one by the g-code program that runs on the Onefinity controller, and you want to connect it directly to the ‘tool-enable’ pin 15 of the 25-pin I/O port, you need to know that these pins are directly the pins of the internal AVR microcontroller that can provide only 3.3 V and very few milliampères of current. Usually you don’t connect a relay module directly to these pins, but you need a driver and / or an optocoupler. This would require soldering a circuit. But recently there exist low triggering current relay modules, with screw terminals. You’ll have to search for a model with 3.3 V trigger voltage and with low trigger current. Often it helps to add the search keyword “Arduino” to the “relay” and “3.3 V”, because the internal AVR microcontroller inside the Onefinity controller is similar to the AVR in the Arduino.
Most people here use this ready-to-use External IoT relay (FAQ) with screw terminals, but this one is only rated for switching 120 V AC loads, not 220 V loads.