The easiest way to run a Multisite network with subdomains is to use wildcard subdomains, because they’ll automagically map anything.yourdomain.com to yourdomain.com and WordPress will in turn translate that for you.
When you’re on shared hosting, you can’t do that. But don’t worry! If you’re willing to do it manually, every time you have a new subdomain, you can still have subdomains! This is really easy, if weird.
Go to manage domains on your Panel and click on ‘Add New Domain / Sub-Domain’
Add your subdomain as ‘mysub.yourdomain.com’ and check the box to remove www (it’s a subdomain, you don’t need it, and it causes weird issues with some plugins).
Set the Web Directory to where you have your main domain installed (normally this will be
/home/username/yourdomain.com ) – yes, I really mean exactly the same. This is what wildcards do for you, but since you don’t have it, you need to do this. It should look like this:
That’s it! Now you just scroll down and press Fully Host This Domain and wait till it’s provisioned. Once that’s done, you can go to mysub.yourdomain.com and it will take you to yourdomain.com! Add in a subdomain within WordPress called ‘mysub’ and everything will work exactly like it should.