Hi, we've got our own pnpscada server, and our organization on this server naturally normally has a subdomain registered automatically by pnpscada that points to our box. But [org-subdomain].pnpscada.com now points to another IP, 196.22.139.148. Our modems have been set to connect to this domain name, and therefore they now connect to the wrong IP and therefore the wrong server, and we cannot read our meters. Please help.
(since I've posted this as a result of a support call via telephone, I've abstracted the subdomain of the organization to protect the caller's privacy)

This should always happen when [org-subdomain].pnpscada.com is not accessible on port 80.
And I see your server is not accessible on port 80 any more (it seems to be routed internally to another box?).
This is a feature, not a bug. The IP you've mentioned (196.22.139.148) is the IP address of Adam, our first box, hosted at Hetzner in Gallo Manor Johannesburg. This has now been a feature for years. For example, ACSA O.R. Thambo logs in at 'acsa.pnpscada.com', which points to Adam also, because they have only opened port 443 on their firewall. Now this is also happening to your organizational domain, because your http port on your internet IP doesn't point to your pnpscada box any more on your router.

Ok, I'll fix this. I thought port 80 was only for html?

The server name, e.g. David.pnpscada.com and [org-subdomain]-david.pnpscada.com will still point to your IP, even though the [org-subdomain].pnpscada.com points to Adam.
This is for the sake of customers that type in [org-subdomain].pnpscada.com into their browsers to log in, because by default browsers browse port 80 (http), so if your clients type it in while port 80 is not configured to go through to the pnpscada server, they would not be able to log in.
Therefore we take advantage of what we call the Glass Wall, by letting them connect to another server, and then routing them to your server after login, on https (port 443).

Ok, I've opened up port 80 again. How long does it take to change back the DNS?

You should reboot your server. The domain registrations happen at startup/connect time.
By default that happens automatically once a day, usually somewhere between 3am and 4am (GMT+2); but you can force that by restarting your server.
We suggest you force a process restart only, by going to the 'restart' menu item (accessible to you since you're an Administrator on your own box); and restarting the server from the web console. It is not necessary to power down and power up your box.