cc2530+cc2591 Not Joining

[FilipDem]

I am already some days running in circles...
I have a Sonoff Zigbee 3.0 USB Plus Coordinator... As many of my devices are battery power, I want to add a router device (esp. to have coverage in the garden for a Sonoff Smart Valve. I use a cc2530+cc2591 and the Create cc2530 router procedure. As firmware I am using the cc2530_cc2591_router_2020_09_29, converted to a binary.
Flashing using a CCLoader with ESP8266 works perfectly from the first trial... 512 blocks and ended with "Programmed successfully"
"Permit Join (All)" is enabled in Zigbee3Mqtt.
However after flashing, the router does not join the network... Debug logs doesn't gave any indication.
I also used the "rejoined" procedure (on - 2s - off, 3 times and then on)... Not joining...
Reflashing... Same (negative) result.
Anyone with interesting insight?
Filip