Hi, not quite as simple as the heading implies. I know how DDNS works but have a couple of questions regarding its operation.

1. I am planning to use VDSL as the primary access and a backup ethernet connection (or more likely a 4g dongle). However, I notice the shortest period for a DDNS update is 180 minutes (3 hours) this seems like a long time if the primary line has failed. Does anyone know when the Router switches to the backup connection if the router immediately notifies the DDNS server or does it wait until the 3 hours??

2. The other thing I have noticed is that when after plugged a USB dongle (using the DHCP settings) it works just fine. But I also noticed that I could no longer access the router using the DDNS name. Looking at the status page it is saying GW IP 192.168.1.1, an internal IP address, rather than the external gateway address to allow me to failover properly. Does anyone know how to fix this?

Thanks in advance for your help.
Iain

RE: 2 - you may be out of luck. Some Mobile Carriers essentially double-NAT you in which case you'd be unable to reach your router management page (or any ports you had open)

Do you know which ones, do and do not double NAT?

OK, think I have resolved my own problems, so thought I would share in case anyone else needs assistance.

I posed two questions.

1. Does anyone know if the router updates the DDNS server when it failsover to a backup line, or do you have to wait until the next DDNS update? ANSWER: The router updates the DDNS server when it fails over and/or the primary line comes back online. It takes a minute or two to update, but it is fast enough.

2. Getting the correct WAN IP to the DDNS server? Well this was a fools question but it shows I am new to using DDNS. ANSWER: In a setting on the DrayTek menu, you can set DDNS to use either the Routers "WAN IP" or the "Internet IP". Put simply, set this to "Internet IP"

I will do more testing over the next couple of days to check the finer details of operation, but I think I have cracked it

haywardi wrote:
OK, think I have resolved my own problems, so thought I would share in case anyone else needs assistance.

I posed two questions.

1. Does anyone know if the router updates the DDNS server when it failsover to a backup line, or do you have to wait until the next DDNS update? ANSWER: The router updates the DDNS server when it fails over and/or the primary line comes back online. It takes a minute or two to update, but it is fast enough.

2. Getting the correct WAN IP to the DDNS server? Well this was a fools question but it shows I am new to using DDNS. ANSWER: In a setting on the DrayTek menu, you can set DDNS to use either the Routers "WAN IP" or the "Internet IP". Put simply, set this to "Internet IP"

I will do more testing over the next couple of days to check the finer details of operation, but I think I have cracked it

Thanks for the update