WAN failover doesn't failover but kinda load balancing

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:

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).

*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).

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

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

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.

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).

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