Sharing Ethernet Connection

We have three users in our house sharing an ethernet cable. It’s plugged into each device as required: 2 x pc (microsoft) and 1 x laptop.

Recently, the two pc’s have lost internet connection completely. One we have noticed oddly can connect to Google sites only: You tube, Gmail etc. We have now noticed that once the laptop has been connected and logged in, if we then put the cable back into either pc fully internet connectivity is restored. This keeps happening on a cycle. How can we stop this and ensure each device is connected to the internet every time without the need to randomly connect the laptop?

I have limited technical knowledge but appreciate any advice.

Thank you.