It looks like they're bracing for a lot of traffic or abuse:

> Limitations

> - DNS names are restricted to that of your tailnet’s domain name.

> - The ports you can specify to expose your servers on are currently to 443, 8443 and 10000.

> - Traffic over Funnel is subject to bandwidth limits. They are not currently configurable.

I was thinking this would be cool to run some live video stuff on, but maybe that's too much bandwidth for now :)