Hi @srsgores,
I think you might have misunderstood the nature and purpose of this option. It’s really meant for use when you have a complicated port forwarding setup so that port 80 on your machine does not correspond to the publicly-visible port 80.
The use of (the publicly-visible) port 80 to validate your control of the domain is mandated by the CA/Browser Forum and can’t be changed; you’re required to validate on that specific port when using this validation method. So, if your ISP blocks that port, you can’t use that validation method at all; there’s no way to request or convince the CA to validate on a different port with this method.
Could you use port 443 instead? Do you have an existing web server listening there? (If so, --nginx might work if you update to a newer version of Certbot, while if not, --standalone might work.)
If not, can you update DNS records in the DNS zone for your domain? That is the third means of validation that Let’s Encrypt offers.