Unable to connect with ppp using nb configuration

[kristoss]

Hey,i am trying to connect a nb sim supporting IPV4-V6 with the nb configuration but it is not possible.But when i am using GSM configuration for the same sim everything works fine.
Any thoughts?

send (AT+QCFG="band",0,0,80000^M)
expect (OK)
^M
^M
OK
-- got it

send (AT+QCFG="nwscanseq",03,1^M)
expect (OK)
^M
^M
OK
-- got it

send (AT+QCFG="nwscanmode",3,1^M)
expect (OK)
^M
^M
OK
-- got it

send (AT+QCFG="iotopmode",1,1^M)
expect (OK)
^M
^M
OK
-- got it

send (ATI;+CSUB;+CSQ;+COPS?;+CGREG?;&D2^M)
expect (OK)
^M
^M
Quectel^M
BG96^M
Revision: BG96MAR02A07M1G^M
^M
SubEdition: V08^M
^M
+CSQ: 99,99^M
^M
+COPS: 0^M
^M
+CGREG: 0,4^M
^M
OK
-- got it

send (AT+CGDCONT=1,"IPV6","iot",,0,0^M)
expect (OK)
^M
^M
OK
-- got it

send (ATD*99#^M)
expect (CONNECT)
^M
^M
CONNECT
-- got it

Script chat -s -v -f /etc/chatscripts/chat-connect -T iot finished (pid 2171), status = 0x0
Serial connection established.
using channel 9
Using interface ppp0
Connect: ppp0 <--> /dev/ttyS0
sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0xcd525e87> ]
rcvd [LCP ConfReq id=0x18 <asyncmap 0x0> <magic 0x1ef02889> ]
No auth is possible
sent [LCP ConfRej id=0x18 ]
rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0xcd525e87> ]
rcvd [LCP ConfReq id=0x19 <asyncmap 0x0> <magic 0x1ef02889> ]
sent [LCP ConfAck id=0x19 <asyncmap 0x0> <magic 0x1ef02889> ]
sent [LCP EchoReq id=0x0 magic=0xcd525e87]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
rcvd [LCP DiscReq id=0x1a magic=0x1ef02889]
rcvd [LCP EchoRep id=0x0 magic=0x1ef02889 cd 52 5e 87]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [IPCP ConfReq id=0x1 <addr 0.0.0.0> <ms-dns1 0.0.0.0> <ms-dns2 0.0.0.0>]
sent [LCP EchoReq id=0x1 magic=0xcd525e87]
rcvd [LCP EchoRep id=0x1 magic=0x1ef02889 cd 52 5e 87]
IPCP: timeout sending Config-Requests
sent [LCP TermReq id=0x2 "No network protocols running"]
rcvd [LCP TermAck id=0x2]
Connection terminated.
abort on (ERROR)
abort on (NO DIALTONE)

Sending break to the modem
send (+++^M)
send (+++^M)
send (+++^M)

Goodbye
Script chat -s -v -f /etc/chatscripts/chat-disconnect finished (pid 2915), status = 0x0
Serial link disconnected.