Your clearOS should be quite powerful. How many WAN you are using? I don't know which client will suit you best but I believe ddclient should work for you.
In what way your domain is blocked? Due to repeatedly update within a short time. I have been using "Dyndns" service, If you ask them about the cause, they usually allow unblocked.
You then need to check the reason. For "Dyndns"
1. usually due to unstable internet connection, it was the case I encountered. The router kept update whenever the connection was made
2. improper router client, "Dyndns" always said that only a few routers are approved. But I don't think it is the case. as long as (1) internet connection does not have problem
3. software update client you use. "Dyndns" provides a list of compatible client. I use ddclient in the linux server.
Then, check your internet connection, do you use ADSL and do you switch off the modem? How frequent your assigned IP changes? I normally do not switch off the ethernet modem. I use HGC, Perhaps the IP changes once every two weeks or even longer. So the update is not frequent But I do set up router to upgrade once every 30 days in case of no IP changes.