I have configured UFW to secure the ports on Ubuntu 20.04 server.
The UFW rules are :
22/tcp ALLOW Anywhere
80/tcp ALLOW Anywhere
443/tcp ALLOW Anywhere
21/tcp ALLOW Anywhere
20,21,990/tcp ALLOW Anywhere
30000:31000/tcp ALLOW Anywhere
3389 ALLOW 149.255.38.47
3389 ALLOW 149.255.38.0/24
3389 ALLOW Anywhere
22/tcp (v6) ALLOW Anywhere (v6)
80/tcp (v6) ALLOW Anywhere (v6)
443/tcp (v6) ALLOW Anywhere (v6)
21/tcp (v6) ALLOW Anywhere (v6)
20,21,990/tcp (v6) ALLOW Anywhere (v6)
30000:31000/tcp (v6) ALLOW Anywhere (v6)
3389 (v6) ALLOW Anywhere (v6)

But the problem i'm having is that it is blocking all the web apps.
80/tcp (v6) ALLOW Anywhere (v6) <-- is this correct ?

How are you connecting to the server?
Where is the server located?
Is it using a static IP?
What actual response do you get when you try to connect to it?
(Are you sure it’s blocked by the firewall?)

Above is IPv6 rule.

How about:
80 ALLOW Anywhere
443 ALLOW Anywhere