@ZorroLion,

From what I can tell, you did everything correctly, unless an address you configured was incorrect. I would recommend carefully looking through the FAQ on the Topic: Configuring WDS on Archer Routers, as anything I could recommend is found in the FAQ. 

Make sure that you read the notes throughout the FAQ, as it is most likely one of these causing an issue, such as incompatibility, or you may need to double-check that you have used an address compatible with your network. Since you are using EU models, I would also recommend visiting our Global 'EN' Forum, as they may have additional information on the topic, or the feature may work differently outside of the US

  @ZorroLion 

Check this thread - it's about similar request as yours. Upon successful configuration WDS status should be Run.

The exteded router (C59) LAN IP address should be in the same network subnet as your AX55 LAN IP address and its DHCP server disabled.

Note that as stated in these guides, WDS may not be compatible even between products of the same company.