NOAH MQTT - how to handle "offline" situation in Cloud

Hello,
due to some WLAN issues with 5GHz my plant went offline. I fixed this and now i only have 2.4 GHz dedicated for the NOAH. The Batteries are shown as “online” in the shine app but not in the Cloud. So polling the data with NOAH MQTT is not possible.
What is the best strategy to fix this without loosing historical data?
Can i remove the NOAH from the plant and re-install? Will it than get the same “sensor” information or will sensor id’s change?
Currently i have a ticket with growatt but they tell me they can not fix this. So in worst case i will have to go the “hard way”.
At the end it would be great if i’d not loose my historical data.
Thx for any help
Günter