How can you do that? Don't you need a proper static IP from the ISP unless you have some sort of a mega business connection?

Edit: thanks for the responses, I didn't know this was even possible.

In my experience, your ISP will only give you a new IP address if your modem disconnects for a while. You can easily use the same IP address for over a year.

You can also use something like DuckDNS to have a backup in case you are away from home and your IP changes, you can still find your server. You could even theoretically write a script that then checks DuckDNS for your IP and updates the record with your Domain Registrar automatically (assuming they have an API)

There are also prebuilt Docker images that will update duckdns for you if you are using docker in your lab

If you mean being able to access your server from elsewhere...

I have a dynamic DNS thingamabob going (a script on a raspberry pi that pings my website a few times per day) and have had no problems. Haven't even noticed my home servers becoming unavailable due to IP address changes for a few years, probably because my ISP (Charter a.k.a. Spectrum) doesn't change my address very often. I use NearlyFreeSpeech for hosting the website and they also handle DNS and have an API for it, so it's all very nice and simple.

You can (and probably should for security reasons) have any entrypoint on e.g. cloud/vps/etc. If you have changing IP where your servers is you can just connect via VPN and then it's pretty seamless even as your IP changes.

More reliable than dyndns (since you never know how long DNS servers are actually caching)

You can get a static IP through my business provider, (Cox), for free. It comes with the business subscription. Getting a business subscription is as easy as signing up for it. I work from home and the guaranteed speed and higher line priority is worth ~$20/month premium. Also no data cap!

Many domain registrars give you an API for DNS updates. Every minute resolve your IP and if it changes, update it. Service won’t be available during propagation but home IP’s don’t change too often

Dynamic DNS has existed for the better part of 20+ years.

Residential ISPs also often provide static DHCP leases that are quasi static IPs.

Some ISPs also sell an addon for a static IP to the service.