Question: how to connect wifi router to laptop without ethernet cable?
Answer: In situations like these, if there is a wired Ethernet network available you can connect to it (even without the Ethernet port) using a USB 3.0, 3.1 or USB-C to Gigabit Ethernet Adapter. Plug the adapter into your laptop's USB port and use a Cat5e/6 cable to connect the RJ45 end to the network.