Not able to access internet on my embedded board using my 4G modue

Question

I have a custom board based on radxa rock 5 and im trying to access internet using my 4G sim. Using the PPP protocol to enable connection and dialling up internet. Im using scripts to automate the dial up process and have tested my SIM using AT commands and my sim works fine. Here are the scripts that I've used.

$ vim /etc/ppp/peers/rasppp
# Hide password when connecting for debugging
hide-password

# Don't need authentication for this phone
noauth

# For call control scripts
connect '/usr/sbin/chat -s -v -f /etc/ppp/peers/rasppp-chat-connect'

# for disconnect scripts
disconnect '/usr/sbin/chat -s -v -f /etc/ppp/peers/rasppp-chat-disconnect'

# Debugging information
debug

# 4G module
/dev/ttyUSB3

# Serial baud rate
115200

# Use default route
defaultroute

# Do not use default IP
noipdefault

# do not use PPP compression
novj
novjccomp
noccp
ipcp-accept-local
ipcp-accept-remote
local

# It is best to lock the serial bus by creating a lock file so that other programs will know that the corresponding serial port is already in use once they discover the existence of this file.
lock
dump

nodetach

# username password (configuration varies by operator)
user ctnet@mycdma.cn
password vnet.mobi

# hardware control flow
crtscts
remotename 3gppp
ipparam 3gppp

# Set the usepeerdns parameter if you want to use the DNS negotiated on the server side.
usepeerdns

$ vim /etc/ppp/peers/raspp-chat-connect

TIMEOUT 15
ABORT "BUSY"
ABORT "ERROR"
ABORT "NO ANSWER"
ABORT "NO CARRTER"
ABORT "NO DIALTONE"

""AT
OK \rATZ

ok \rAT+CGDCONT=1, "ip","airtelwap.com"

ok-at-ok atdt#777
CONNECT \d\c

$ vim /etc/ppp/peers/rasppp-chat-disconnect

    ABORT "ERROR"
    ABORT "NO DIALTONE"
    SAY "\NSending break to the modem\n"
    ""\k""
    ""+++ATH""
   `SAY "\nGood bye ! \n"

And then running the dial up process

sudo pppd call rasppp &

The problem im facing right here is, im able to ping 8.8.8.8 once the dial up is done but not able to access internet and browse any sites. ipconfig shows my ppp0 up there with the IP address too. Need some immediate help, would be grateful for any ideas on how to fix this.