DDNS load balance and failover


I am interested in the Balance 20 router and want to load balance between DSL and Cable and have 3G for failover.

What would be the DynDNS behaviour if I configure DDNS to Cable WAN and that goes offline? Would DDNS update my DynDNS account via DSL WAN?

And if Cable WAN and DSL WAN go down, would the Balance 20 update DynDNS via 3G then?


Hi Hans,

The DDNS setting is per WAN interface basis, if you put in the same DDNS credential in all WAN interfaces, the last WAN which update DDNS record will overwrite the previous records. So, it is recommended to register different DDNS hostname for each WAN/Cellular.

Do take note that if the WAN/Cellular is getting Private IP from the ISP, then Port Forwarding would be required on the upstream ISP modem/router if Inbound access needed.

Thanks and regards,

This is not what I am looking for. A domain name per redundant route will certainly not work with all kinds of applications. What prevents you to handle that from the Preplink device? The router has the knowledge about the failure, right?

Hi Hans,

Peplink could achieve what you looking for, but assigning the secondary WAN and 3G as Backup Priority connection type, this will allow the secondary WAN or 3G to update DDNS during the failover.

Thanks and regards.

Hi Wei-Ming,

Really? Let me be more precise. I am looking for the following DDNS handling.

  1. Normal desired state.
    WAN1: UP with DDNS - WAN2: UP - 3G: COLD STANDBY

  2. WAN1 fails and WAN2 takes over the incoming traffic. (When WAN1 restores its service, DDNS shall return to state 1.)

  3. During WAN1 failure WAN2 fails as well.
    WAN1: FAIL - WAN2: FAIL - 3G: UP with DDNS

In my opinion that would be straightforward.

Would that be possible with the current firmware? Or would that be a feature request?

BTW: Is there a dealer in Berlin that has the Balance 20?

Best, Hans

P.S.: Of course in all states the same DynDNS domain. Normal users shouldn’t notice anything. And my SIP clients can only handle a single domain, too.

DDNS services do not operate this way, this is not a Peplink firmware issue. The DDNS service simply looks for an update and will use the most current one on record, so having WAN1 and WAN2 active with the same DDNS account will not work.

To achieve true inbound redundancy you should look at getting static IP addresses and using the Authoritative DNS feature available on the Balance 210 and higher.

I know how DDNS service works and how records are updated. I am just asking whether the Balance 20 can update this record in a clever way.

You are saying it can’t.

Going for static IPv4 is no longer an option I think.

Thanks Hans, I have moved this thread to the Feature Requests.

Hi Hans,

If I understand correctly, you want to set WAN 1 as priority 1 and WAN 2 as priority 2. I.e. WAN 1 and WAN 2 will not be active at the same time. You configure both WANs’ DDNS settings to be the same. Are you asking whether the Peplink will update the DDNS service accordingly so that your users can always reach the Peplink unless both WANs are down? If so, the answer is yes. We should have a customer using the Peplink in such way.

Incorrect. Please ask yourself the question: would you (as a private person) like to pay for 2 internet connections and want to miss load balancing for outgoing traffic? No!

Please read carefully what I wrote above. I think I was quite clear describing the 3 states. And I think the thread title says it already.

I think I will research whether RouterOS or OpenWRT would be a suitable platform. I am not keen to do router scripting stuff, but if it helps to get what I desire…

Hi Hans,

As explained earlier, the feature you requested is not supported in current firmware, we will review this feature and the feasibility to include it in our future firmware.

Optionally, I found this website which stated “* Round robin DNS supported (Multiple IP addresses for 1 hostname)” in it’s feature list, which might fit your requirement.

Thanks and regards.

Hi Guys

I have a similar project at hands, basically its the following:

Two WAN’s with dynamic ip’s, and doing multi-wan via round robin for the outbound. The main idea is to access remotely to peplink/internal network via a single dynamic dns, that means that when configuring a dydns provider it should point to the two wans available, and if possible balance the inbound connections.

Imagine there are 20 connections accessing example.dyndns.org via WAN1 and it becomes saturated, so the appliance should only accept and redirect the connections to WAN2.

Is this possible ?

Or to do the following, create a dydns failover, like both WAN’s configured with the same dyndns name but only one responds, if WAN1 then it would respond automatically to WAN2, the issue for me is that both are active because I’m doing outbound load balancing.

Any ideas ?



Look like Inbound Overflow algorithm is needed. This is depending on DynDNS provider. FreeDNS is a good example to provide such service. However it is using Round Robin.

Basically concept of DynDNS is not design for inbound load balance access. You will in trouble if WAN1 (for example) provides last IP update to DynDNS server then it is down. User request will be redirect to WAN1 even it was down. Please use different hostname.


Thanks for the reply.

Is peplink compatible out of the box with FreeDNS.

Do you know any DynDNS provider like FreeDNS but also uses Inbound Overflow algorithm ?


Best Regards


May be you can test it out. This DynDNS is based on my google result.

Peplink Balance, upon receiving the DNS query, returns to the client computer the IP addresses of www.foobar.com that correspond to available WAN links. For example:

  • If both WAN1 and WAN2 are available, then both the IP address that corresponds to WAN1 and that of WAN2 are returned.

Based on the above quote, if the Peplink has two WAN’s with fixed IP address, then it can do inbound load balance using inbound interface overflow algorithm ?




Overflow is not supported. We do inbound load balance similar to Weighted Balance by default. You may change to Priority by configure WAN priority via Network > DNS Settings > Default Connection Priority.