Ethernet disconnected after sleep

This week I connected my Macbook Pro 2012 (OSX High Sierra) on ethernet since my wifi signal is terrible. It worked perfectly: super fast internet. But I noticed that when the Macbook woke up after sleeping, the internet was gone. In the Network Preferences it said that the cable was not connected. YES IT WAS. Plugging the cable out and in, on both sides, it kept saying No Cable. The only thing that worked was a hard reboot.

I read some threads here on this topic. I'm not alone! I tried some stuff, but found only one solution.

Solution that worked in my case:

1. Go to Network Preferences.
2. In the left pane, click on Ethernet.
3. Click Advanced
4. Click on tab TCP/IP.
   In my case, which is the standard option I guess, at Configure IPv4 the option DHCP was selected.
5. Change it to Manual.
6. Now, type the IP-adress you want to use as a fixed address. To find out which one is free, check the Admin page of your router. You're probably able to set the range of dynamic assigned IP-adresses. Pick an address outside of this range. You don't want to use a fixed IP-adress that also might be assigned dynamically to other devices.
7. Enter for the subnetmask: 255.255.255.0
8. Enter the IP-adress of your router. In my case, that is 192.168.01. Again, check your router to see what the IP-adress of your router is.
9. Configure IPv6: Set it to Disabled.
10. Enter your DNS IP-adresses. I use the Google ones: 8.8.8.8 and 4.4.4.4
11. Boot your Macbook.

To be sure that you're on cable, disable WiFi. What I also did in the left pane, was changing the order of the connections: Ethernet first, Wifi second. In that case, you will always use cable if it's available.