Note: the admin pages have been redesigned since the screenshots in this documentation, though the functionality is essentialy the same. The documentation will be updated to match.... soon.
To set an A Record on a domain registered with IONOS (formerly 1and1), use these instructions.
In step 5, use the IP Address 83.136.248.56
Do NOT set an AAAA record. If there is an AAAA record present then delete it. You should only have an A record.
Note that changes to your DNS settings can take up to 24 hours to propagate through the Internet.