I’m asking me if it will run in any problems if I would have 2 controllers (1 zwave, 1 zigbee) and also some devices in both protocol running parallel at the same time? the reason I’m asking for is because they both run with 868mhz (in EU) and I’m not sure if they intereference each other?!
No - no problem with this.
They run on different frequencies. ZWave is 868, but ZigBee is 2.4GHz.
I see, 2,4Ghz seems the default frequency for zigbee. Good to know! Well, then I modify my question a bit: could it slow down/brake my 2,4ghz wifi network?
No - LOTS of devices run on 2.4GHz - WiFi, Phones, Bluetooth, ZigBee, Ant… There’s a wide spectrum and mostly they will work ok together. You might need to play with channels to avoid interference in some cases.