Use LTE only as fallback

Hi,

I have a Turris Omnia with the 3G/LTE kit. We use the Omnia when we travel, to make an easy connection to whatever network we can use and use 3G/LTE as fallback when there is no cabled or wifi network available.

It works quite good, but the only thing I miss at this time, is for the Omnia to use the “cheapest” connection available for all traffic and use LTE/3G only when cabled and wifi are not connected/available.

Currently I manually enable/disable the LTE/3G interface, to prevent it being used. That works fine, but only if the used cabled/wifi connection doesn’t drop. If that happens, everything grinds to a halt and I have to manually enable LTE/3G.

So my question:

Is there a way (maybe with static routes?) to make Omnia use connections for all traffic in a specific order (1. Cable, 2. Wifi, 3. LTE/3G)?

This seems to happen to some degree already and most traffic is routed through cable/wifi in stead of LTE/3G, when cable/wifi is back up, but there is still traffic going out over LTE/3G, according to the package and MB count.

Hope there is a solution for this?

I found something about your problem.

Citation: Now if everything went well all your traffic between the router and the Internet should go through the LTE interface. That means that the connection through the WAN interface will not work . If you want to use the LTE card as a backup Internet connection you need to go through [the mwan3 tutorial] (Failover to LTE using mwan3 [Turris wiki]).

https://wiki.turris.cz/doc/en/howto/lte_modem_install

Thanks.

I missed that last bit in the manual apparently :wink:

Will take a shot at mwan3.

You should change the metric value of the interfaces in the routing table. Lower has the higher priority.

In Linux can be done by ifmetric cmd. But no idea if it is available here, otherwise you can do by route cmd, delete and add with new metric value.

For example:
eth2 interface has metric 0
LTE interface has metric 50

means when eth2 not available use LTE.

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mwan3 works like a charm! It is a lot more versatile in comparison to adding metrics to your interfaces. It also adds (when using the LuCi package) online and troubleshooting information.

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