Thanks for your answers so far.
I am using an Asus RT-AC88U Dual Band Gigabit router which is around 15m away.
Rachio is connected via DHCP but assigned a fixed IP and on the 2.4 band (-70 dbm)
Signal strength is good with 5.5 TX and 2.5 RX
I cannot see anything in my logs that indicates a loss of wireless connection from my end.
Is there a log on the Rachio I can access?
They are 24 VAC. Also, the entire system was up and running for a while without any issues.
No master valve installed. Pretty simple setup with no sensor or master connection.
I have tested the wire itself which are working as intended. Again, they are shielded above ground in a conduct and only 2 meter long. Also no visual issue on the wire itself
What I also notice is that the Rachio just died and lost power. I already bought a new power adaptor but I also tested both and they actually produce what the Rachio is needing. So i can assume that the adaptor itself is also not the issue.
At this stage all is pointing to a faulty Rachio. I have contacted the support and wait for their answer.