WAN failover doesn't failover but kinda load balancing

Routers
1

MT6000, fw 4.5.4 r4 (2023-12-12 06:58:59), WAN connected by Eth1 + WiFi, Multi-WAN config: Enable Interface Status Track: disabled for all interfaces*, interface priority:
1

Despite a stable LAN connection to my hardware firewall I am kicked out every few minutes as soon as I connect WiFi, reason is a changed source IP (LAN IP vs. WiFi IP).
Pls fix, failover means WiFi must not be used when LAN is available (just imagine the failover line was a metered connection where I had to pay for traffic).
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*help says

If tracking is disabled, the device will assume that the interface is connected to the Internet when the interface is connected (e.g. if a cable is plugged in and an IP address is acquired).

2

Just to get that right, you connect your MT6000 by LAN and WiFi?

3

Yes, in my tests that’s what I did.
On the longer run I’ll use tethering to 5G to have redundancy.

4

Does the same happen when you keep interface tracking enabled?
Why is it turned off anyway? In that case, only some hardware failure would be relevant - but if just the internet connection drops, the router won’t be able to understand it.

5

Does the same happen when you keep interface tracking enabled?

yes, already the 1st connection I tried is done by the wrong interface (WiFi-IP).

For one failover for hardware outages is a legit approach but the actual reason is to reduce error sources (easier debugging).

6

FWIW:
Rearranging Interface Priority and pressing [Apply] solves it until WiFi* is dis- and reconnected.
So some step appears to be missing in ifup/down or alike networking scripts.

* dis- and reconnecting Eth1 does not have this effect