Zigbee Network on two floors

Hello guys,
let me describe my issue and if someone can give me some guidence.
I have 2 Floors:
1st Floor only end devices and 1 Linux with docker container of zigbee2mqtt + mosquitto + Sonoff Zigbee 3.0 Plus dongle
2nd Floor I have 2 Ikea repeaters and a lot of battery powered end devices.

The issue is that on the 2nd floor there is no enough covrage and this is causing issues of pairing and basic functioning of the devices. I have one more Sonoff Zigbee 3.0 Plus dongle and Raspberry Pi. Can someone give me the best setup for that?