@Jonas123 With the slave Deco powered on, hold on the reset hole for 1s. Then you can set it up via the Deco app.

Recently, there is an issue reported by one end-user; he failed to connect this Synology NAS DS918+ to the Archer AX6000 with Link Aggregation enabled. Per customer said, the network diagram is...

@RaymondvH Hi you can refer to this FAQ to switch slave Deco to main Deco: https://www.tp-link.com/support/faq/2400/ If the Deco M9 plus is V2 and you want to use the new features, you can keep Deco...

@Hismuth Hi, connect the slave Deco to the main Deco directly, bypass the switch and verify whether the ethernet backhaul works. You can read Q6 of the article attached below:...

@RalfH Hey, we can get some details to do the further analysis first. 1. What is the led status of Deco when you lose internet? Do both wired connections and wireless connections have the same issue?...

@b-s-a The Deco M9 Plus does not support 3/4G router mode, which means it cannot work with the 4G modem together.