I recommend that you read and understand the document: AN07 - How to configure TransPort WR for Cellular Problem Detection and Recovery using Sure Link Wizard
on this page: https://www.digi.com/support/productdetail?pid=5499&type=documentation
This document will explain everything you're configuring in detail so you understand how it all works.
If you need some CLI commands (telnet/ssh or 'Execute a command' in the GUI) to run then you can use these:
ppp 1 settledly 20
ppp 1 pingip "220.127.116.11"
ppp 1 pingint 60
ppp 1 pingint2 10
ppp 1 pingip2 "18.104.22.168"
ppp 1 pingresp 10
ppp 1 ip2count 3
ppp 1 pingdeact 60
ppp 1 sscnt 50
ppp 1 sssecs 180
ppp 1 rebootfails 50
modemcc 0 link_retries 20
modemcc 0 stat_retries 30
config 0 save
ppp 1 deact_rq # Note, this last command will restart the PPP interface to make sure all these settings are running, expect to lose comms for a moment after running this.
These settings will...
send a ping every minute to 22.214.171.124, allowing 10 seconds for a response
if a failure occurs, switch to a 10 second interval
after 3 failures, switch to pinging 126.96.36.199 at 10 second intervals
after 60 seconds of failed pings, the PPP interface will restart
if the PPP interface is restarted, but fails to reconnect correctly to the network for 20 consecutive attempts, the radio module will be restarted
if the PPP interface continues to fail to reconnect correctly to the network for another 20 consecutive attempts, the radio module will be restarted again
if the PPP interface fails to reconnect correctly to the network for 50 consecutive attempts, the router will be rebooted
I've also allowed to 50 lost packets in 180 seconds as a trigger to deactivate and restart the PPP link, any more than 50 will restart the PPP interface.
Ben - Digi Support