Issue connecting laptop and RPi via 6LoWPAN over BLE

Hi Group,
     I am trying to establish a 6LowPAN over BLE connection between my
Ubuntu Laptop and Raspberry Pi 4B. Laptop is running Ubuntu
5.8.0-48-generic #54~20.04.1-Ubuntu and my RPi is running custom
yocto-based Linux distro with kernel version 5.4.x version.

I am facing an error of 0x12 when trying to establish to Rpi from the
laptop as below:

root@root1-Nitro-AN515-55:/home/root1# lsmod | grep 6low
bluetooth_6lowpan      28672  0
6lowpan                40960  8
nhc_fragment,nhc_dest,nhc_ipv6,bluetooth_6lowpan,nhc_hop,nhc_udp,nhc_mobility,nhc_routing
bluetooth             581632  31
btrtl,bluetooth_6lowpan,btintel,btbcm,bnep,btusb
root@root1-Nitro-AN515-55:/home/root1# echo 1 >
/sys/kernel/debug/bluetooth/6lowpan_enable
root@root1-Nitro-AN515-55:/home/root1# dmesg
root@root1-Nitro-AN515-55:/home/root1# echo "connect DC:A6:32:F2:CB:46
1" > /sys/kernel/debug/bluetooth/6lowpan_control runn
root@root1-Nitro-AN515-55:/home/root1# dmesg
[239155.542994] Bluetooth: hci0: request failed to create LE
connection: status 0x12

Running btmon in another shell resulted in the following log as attached.

Additional Info: using bluetoothctl between my Laptop and RPi s
successful but 6LowPAN is unable to go through.

Any missing from my end?

Thanks,
Nagesh.