Does it need to be done on the router, or on every computer?
How do you block a port on a tablet or a phone?
According to what I was able to glean from the article, you must have root access to the device to be able to change this setting, as the port and the TR-069 protocol are not on the end-users standard menu options.
Perhaps one of the more knowledgeable FReepers who work closely with these devices can suggest a workaround.
Besides blocking, you can also forward that port to an IP address that is not being used on your sub network. That way if blocking fails, any traffic for that port would be directed to a device that does not exist.
Depending on how their networks are configured, if you block access to the ACS server, you could possibly kill your internet, if your “router”(they aren’t REALLY routers, they’re more like ‘smart transceivers’) has to ‘call home’ and pull down configuration when they are booted up.
I would hope they don’t have their networks setup to run that way though. That would be one hell of a central point of failure if there are ever issues on their end. They probably have a hierarchy of servers; local/regional/central to reduce overhead and build in redundancy.
As an end user, I wouldn’t be terribly concerned about this. Well, maybe a little. It might be good to be aware of it.