It's kinda clutching at straws here but could there be any kind of firewall or router blocking the connection?

Bitcoin 111 errors are because of RPC access being blocked. Although slightly different, I've had nightmare problems in the past with faucets that refuse connections when used on webhosts rather than a dedicated VPS setup. Even jailbroken hosting plans don't give as much access as they would have you believe.

An NS record is pretty important and a lot of hosts won't allow you to change one (even if you ask their support for a record change). If you come up against a brick wall, my suggestion is that you try to host the seeder and website yourself on a cheap VPS. You can't beat DigitalOcean's VPSs for the flexibility you get at such a small cost if you find that the hosts aren't accommodating your requests.