@Rico63,

From what I can tell, you should have no difficulties with this setup after looking at the specs. Range Extenders can accommodate almost any wi-fi connection that you can throw at them, they just will be limited based on the technology of the router. The aim for TP-Link Extenders is for them to be compatible with any existing router.

The RE 220 is: 

• Compatible with 802.11 b/g/n and 802.11ac Wi-Fi devices

and I believe that your century link wi-fi modem is:

• 2.4 GHz 802.11 b/g/n
• 5 GHz 802.11 ac (WiFi 5)