Server only working on the same ISP?

[DodoKrastavac]

Due to the fact it's summer break a couple of friends and I decided to make a Minecraft server...

The issue is it works completely fine with people outside my network, like it's supposed to. But only if they have the same ISP.

A couple of things to not: I use cloudflare's DNS

I tried putting the local address in DMZ

I turned off all the firewalls on my network and computer

I turned off WAN blocking

People who's connection gets blocked (because they're on a different ISP) turned off their firewalls on their computers

We disabled our antivirus software (those of us who have it)

 

Any help to this would be appreciated as I'm at a dead end here. Again it works with people outside my network on the same ISP, but not with people using a different ISP.

[Master Disaster]

1 minute ago, DodoKrastavac said:

Due to the fact it's summer break a couple of friends and I decided to make a Minecraft server...

The issue is it works completely fine with people outside my network, like it's supposed to. But only if they have the same ISP.

A couple of things to not: I use cloudflare's DNS

I tried putting the local address in DMZ

I turned off all the firewalls on my network and computer

I turned off WAN blocking

People who's connection gets blocked (because they're on a different ISP) turned off their firewalls on their computers

We disabled our antivirus software (those of us who have it)

 

Any help to this would be appreciated as I'm at a dead end here. Again it works with people outside my network on the same ISP, but not with people using a different ISP.

Does your public IP address begin with 10 or 160? You might be behind a CGNAT at your ISP.

[Lurick]

4 minutes ago, Master Disaster said:

Does your public IP address begin with 10 or 160? You might be behind a CGNAT at your ISP.

100.64.x.x through 100.127.x.x are the official CG-NAT IP ranges but yes, 10.x.x.x is also something a lot of ISPs do use.

[DodoKrastavac]

7 minutes ago, Master Disaster said:

Does your public IP address begin with 10 or 160? You might be behind a CGNAT at your ISP.

 

3 minutes ago, Lurick said:

100.64.x.x through 100.127.x.x are the official CG-NAT IP ranges but yes, 10.x.x.x is also something a lot of ISPs do use.

Was, long ago disabled CG-NAT. Very possible this might be the issue. Took me 17 phone calls to my ISP to disable CG-NAT ~7 months ago due to them being incompetent. And now I check my IP and see it's 100.85.x.x and am going to make an angry phone call yet again.