Shelly Dimmer 2 Problems

[Poverino]

We are in the process of automating our house. We purchased various Shelly items for this purpose. It's fun to do and it keeps us busy. With trial and error it gets better and better.

More than 10 Shelly plugs work correctly. All equipped with a fixed IP address. Now we have three Shelley Dimmer 2 modules. Everything worked perfectly until one of the lamps connected to it spontaneously went on and off. These lamps are equipped with LED and consume a maximum of 30 Watts each. I have reset the module and disconnected it from power several times, but it remains stuck in the "Pending Connection" mode. I have now ordered 2 new Shelly Dimmer 2 that arrived today and I immediately connected a new module.

To my great surprise, the other two modules no longer have an on and off button in the Shelley App. Via my Homey Pro where everything comes together, I can simply access two modules and they work.

My question now is. Why is it that the on and off buttons in my Shelly App have disappeared? And why is it that 1 module gets stuck in Pending mode

I have only made three FLOWS, but I will continue to do that step by step. Provide the plugs with a fixed IP on advice so that it continues to work flawlessly in the event of a power outage. The 2 working Shelly Dimmers also have a fixed IP address, which is all recorded via the DHCP of my ROUTER. (TP-Link which is connected behind a Ziggo Modem/router).

In short, what is going on now? Can I only connect a limited number of units in the Shelly App? What am I doing wrong? I hope to have provided you with enough information so that we can resolve the issue.
Ps. Modules are connected without 0 wire