I’ve deployed my Pi Zero W with the IoT HAT out in the field and it just barely works. It has excellent LTE signal. When it’s connected, AT commands show that it has -61 dBm RSSI and 4.19 dB SINR on LTE BAND 12, CAT-M1. However, I can’t maintain a PPP connection. Once it connects, it only lasts for a few minutes before getting kicked off and having to start over again. I have a PPP connection for about 2 minutes out of every 10.
This what my ppp peer file looks like:
# /etc/ppp/peers/provider
/dev/ttyUSB3 460800
# The chat script, customize your APN in this file
connect 'chat -s -v -f /etc/chatscripts/chat-connect -T h2g2'
# The close script
disconnect 'chat -s -v -f /etc/chatscripts/chat-disconnect'
# Hide password in debug messages
hide-password
# The phone is not required to authenticate
noauth
persist
# Debug info from pppd
debug
# If you want to use the HSDPA link as your gateway
defaultroute
# pppd must not propose any IP address to the peer
noipdefault
# No ppp compression
novj
novjccomp
noccp
ipcp-accept-local
ipcp-accept-remote
local
# For sanity, keep a lock on the serial line
lock
modem
dump
updetach
# Hardware flow control
nocrtscts
remotename 3gppp
ipparam 3gppp
ipcp-max-failure 30
Sometimes this is what the ppp log shows when it loses its connection:
pppd[1131]: rcvd [LCP TermReq id=0x2c]
pppd[1131]: LCP terminated by peer
pppd[1131]: Connect time 2.8 minutes.
pppd[1131]: Sent 1425461 bytes, received 1031159 bytes.
pppd[1131]: Script /etc/ppp/ip-down started (pid 1272)
pppd[1131]: sent [LCP TermAck id=0x2c]
pppd[1131]: Modem hangup
pppd[1131]: Connection terminated.
pppd[1131]: Script /etc/ppp/ip-down finished (pid 1272), status = 0x0
Other times, the ping test in the script that runs ppp fails, so it runs poff and pon. I even changed the ping command to -c 10 instead of -c 1 to make sure it’s REALLY disconnected instead of just 1 failed ping, and that didn’t seem to help.
I’d be happy to provide more context if you have any questions. Any help is greatly appreciated.