Hi Ben, in my experience it can sometimes take a while for a restarted server to propagate the new IP via the DNS network. Generally this is less so with 'better' DNS providers (in my experience ISP DNS commonly override the TTL configured by TKL HubDNS and don't update their records as often as they probably should).

I have found that using Google public DNS (8.8.8.8) as your default DNS provider (rather than your ISP) somewhat mitigates this issue. But you will still have a little wait (it should usually happen within 5-10 mins). Also I have noticed that this issue doesn't occur with a new server. I assume that that is because initially the domain name doesn't exist in the cache so it updates immediately, whereas once you have used it it has an IP in the cache and won't update until the TTL expires.

If you plan to do this a lot (i.e. start/stop your server) and the delay to update the domain name/DNS is going to be an issue (and the Goolge DNS is not an adequate workaround), then I suggest that you consider getting an AWS Elastic IP (a static IP that you can attach to your server). They are free for one IP per server, although the flipside of that is that AWS charges for the Elastic IP while it's not attached to an instance - including if the server isn't running (currently $0.005/hr i.e. half a cent per hour). You'll also get charged once you reach the free threshold of 'remaps' (unattaching and reattaching the Elastic IP from/to your server), currently this threshold is 100 per month (and the charge beyond this limit is currently $0.10 per remap).