D-link lte router on a wcdma mobile network

Hi everyone !

I'm new on this forum and I have a question about the mobile configuration of an LTE modem which is on a d-link dw 921 rev. C1

After the fresh install of OpenWrt, I've successfully connected it to a Free Mobile 4g network (France) following the UCI instructions, and it automatically and perfectly re-connect on boot/reboot.

But now I use it in a place without an lte connection, only umts/wcdma and the modem can't automatically connect to it.
The only way I found to semi-automatically connect the lte modem is this homemade script which looks like this :

#/bin/sh

APN="free"
DEV="/dev/cdc-wdm0"
PIN1="1234"

echo "signal info :"
uqmi -d $DEV --get-signal-info
echo "pin unlock..."
uqmi -d $DEV --verify-pin1 $PIN1
sleep 1
echo "unblock card..."
uqmi -d $DEV --stop-network 0xFFFFFFFF
sleep 1
echo "connection to $APN..."

while [ "$(uqmi -d $DEV --get-data-status)" != '"connected"' ]
do
	uqmi -d $DEV --start-network --apn $APN --keep-client-id wds
	sleep 2
done

#echo "up wwan..."
#ifup wwan
echo "done."
exit 0

and typically returns this :

signal info :
{
	"type": "wcdma",
	"rssi": -84,
	"ecio": 8
}
pin unlock...
unblock card...
"Invalid handle"
connection to free...
/dev/cdc-wdm0
"Call failed"
"Call failed"
"Call failed"
"Call failed"
"Call failed"
"Call failed"
"Call failed"
89937264
done.

As you can see there is some attempts before connecting, and after about 14-16 hours it disconnects then a reboot+re-executing the script is the only way to reconnect...

So how I can make the lte modem automatically connects to the network and stay connected/re-connects automatically ?
Thank by advance for your answers :slight_smile:

PS : sorry for my english