I have recently upgraded my Draytel 2820 routers to the latest firmware and noticed that the Dynamic DNS setting has an auto-update interval set, by default, to 60 minutes.

Is this a recent addition? If so, it's causing me a massive problem because it causes me to fall foul of DynDNS's abuse rules:

Client updates at regular intervals: Clients should only send updates when a change is detected, but some are programmed to send updates at scheduled intervals, e.g. every five minutes or every hour.

(http://www.dyndns.com/support/abuse.html)

The problem I have is that there is no way to switch this off and have the router update DynDNS only when the IP address has changed.

Is this a bug, or have I missed some new way of setting this up? Right now, I can't reenable this as I will just get blocked again.

I don't have the right answer for you. I thought the newer routers played well with DynDNS. With the older routers, the only DNS provider which worked well with an almost static IP was DtDNS. I never get abuse e-mails from them or e-mails saying I have not logged into the account for so long and if I don't they will disable the account.

But as long as you set it to the maximum value (14400 minutes - 10 days) they don't seem to mind. You will always get some unnecessary updates if the router reboots etc.

Not been a problem for me. Shame that the log only shows the time it does the update and not the date - I can't tell when they have actually occurred!

There doesnt seem to be an option of a time when it checks - so when does it update it...?

the option is how often it updates - on the initial dynamic DNS. setup page as "auto-update interval". values. can be 1 to 14400 minutes

The real problem is twofold:

1. The Vigor 2820 only supports updating DynDNS on a regular basis, rather than when the IP address is detected as having changed. This breaks the first rule of their abuse policy: "Client updates at regular intervals: Clients should only send updates when a change is detected, but some are programmed to send updates at scheduled intervals, e.g. every five minutes or every hour."

2. Draytek routers are not officially supported by DnyDNS (see https://www.dyndns.com/support/clients/hardware/), probably as a result of point 1.

I have set the update interval to 1440 (= 24 hours) and will see how I get on.