# How to setup a LAN (primary) to SIM (secondary) failover for continuous connection.

**URL:** <https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156>\
**Category:** Digi TransPort WR (Series)\
**Tags:** lan, to, sim, failover\
**Created:** [July 18, 2022, 11:06am UTC](https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156 "2022-07-18T11:06:45Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Sherwin](https://avatars.discourse-cdn.com/v4/letter/s/7ea924/32.png) [@Sherwin](https://forums.digi.com/u/Sherwin)\
**Post date:** [July 18, 2022, 11:06am UTC](https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156/1 "2022-07-18T11:06:45Z")

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Hello,

One of my clients sites has a ADSL connection which is flakey and loses connection periodically. We need to keep the server visible via a DDNS using the ADSL via Eth1 as the primary route and when it fails, to switch over to the 4G comms until the ADSL service has returned.

Do you have documentation or knowledge base that covers this?

Thank you.

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**Author:** ![NicholasYourIoT](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/nicholasyouriot/32/27_2.png) [@NicholasYourIoT](https://forums.digi.com/u/NicholasYourIoT)\
**Post date:** [July 18, 2022, 8:49pm UTC](https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156/2 "2022-07-18T20:49:02Z")

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What product are you using?

Nicholas Wilson  
Your IoT  
[https://www.YourIoT.com.au](https://www.YourIoT.com.au)

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**Author:** ![Sherwin](https://avatars.discourse-cdn.com/v4/letter/s/7ea924/32.png) [@Sherwin](https://forums.digi.com/u/Sherwin)\
**Post date:** [July 19, 2022, 10:41am UTC](https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156/3 "2022-07-19T10:41:30Z")

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It’s a Digi Transport WR21 router.

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**Author:** ![NicholasYourIoT](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.digi.com/nicholasyouriot/32/27_2.png) [@NicholasYourIoT](https://forums.digi.com/u/NicholasYourIoT)\
**Post date:** [July 20, 2022, 1:04am UTC](https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156/4 "2022-07-20T01:04:07Z")

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Take a look at Application Note 41 and 71 which you can find here:  
[https://hub.digi.com/support/products/cellular-routers/digi-wr21/?path=/support/asset-collection/wr21-application-notes/](https://hub.digi.com/support/products/cellular-routers/digi-wr21/?path=/support/asset-collection/wr21-application-notes/)

Those should be able to point you in the right direction.

Nicholas Wilson  
Your IoT  
[https://www.YourIoT.com.au](https://www.YourIoT.com.au)

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**Author:** ![Sherwin](https://avatars.discourse-cdn.com/v4/letter/s/7ea924/32.png) [@Sherwin](https://forums.digi.com/u/Sherwin)\
**Post date:** [July 21, 2022, 9:05am UTC](https://forums.digi.com/t/how-to-setup-a-lan-primary-to-sim-secondary-failover-for-continuous-connection/23156/5 "2022-07-21T09:05:29Z")

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Thank you. 🙂