How to switch secondary WAN to Hot-Standby?

[Ubimo]

Hello
I use a Huawei LTE stick as a backup secondary WAN in case my primary WAN fails.
While the Dual-WAN, failover, and failback functionalities are working well, they are not fast enough.
How can I switch the secondary WAN to Hot-Standby mode?

 

[eibgrad]

What constitutes too slow? At least for my ASUS RT-AC68U, the default is 6 secs (3 sec interval * 2 consecutive failures). If you change too quickly, you may end up w/ a lot of false negatives.

[Wireless Router] How to configure the Auto Network Detection while enabling the Dual WAN? | Official Support | ASUS Global

 

[Tech9]

This thing may or may not fail over to Secondary ISP and may or may not fail back to Primary ISP after the service is restored. If it switches connections at all even being slow - don't touch, it won't get any better. Asus component, copy/paste over the years in different firmware, never fixed.