Hi! Are you using Cloudflare?
If you are using Cloudflare and the A record is configured, you should still be able to access the website through your domain name url.
Most likely you get the above message in Sitejet (in the Domain Manager area) if your A records are proxied on Cloudflare (basically Sitejet can’t verify the settings because they are “hidden” by Cloudflare).
Just make sure that those A records are not proxied (they are DNS only) in Cloudflare.