SIM800L and UNO can't request web page

Question

I know this module is super old but the network I am on still uses GPRS so should work.

This is the module: I am using the Adafruit example scipt FONAtest. I can connect to GPRS

    <--- SHUT OK
    ---> AT+CGATT=1
    <--- OK
    ---> AT+SAPBR=3,1,"CONTYPE","GPRS"
    <--- OK
    ---> AT+SAPBR=3,1,"APN","live.vodafone.com"
    <--- OK
    ---> AT+CSTT="live.vodafone.com","",""
    <--- OK
    ---> AT+SAPBR=3,1,"USER",""
    <--- OK
    ---> AT+SAPBR=3,1,"PWD",""
    <--- OK
    ---> AT+SAPBR=1,1
    <--- OK
    ---> AT+CIICR
    <--- OK
FONA>

There is credit on the SIM so it has data for sure, I can also send SMS.

There are several different approaches people seem to take (altering AT commands) to persuade this device to work, pretty sure I have tried all of them :) I always get a timeout when trying to read or GET a webpage.

I have tried several combinations via terminal and I seem to connect ok but get no further. It has worked once, but that was in a different part of town.

How do I check that the GPRS is actually connected? Any troubleshooting tips?

There is a dedicated 2A 5V connected to the unit, it isn't dropping out AFAIK. Do you have a rock-solid AT sequence that always works?

Also, there seem to be SAPBR commands that don't work at all, not sure why?

Answer 1

It highly depends on the URL you are trying to fetch.
Those modules DO NOT understand secure HTTP/S. They only understand plain unsecure HTTP.
Most web pages nowdays don't offer unsecure HTTP access and always redirect the request to a HTTP/S server. So in my opinion the usefulness of those devices is very limited when it comes to internet access.

If you have full control over the web server you should disable the enforcement of a secure connection.

Beyond that. The sequence you posted is just for activating GPRS.

I also found the FONA sample for fetching a page not very reliable but I was able to request the page multiple time. Perheps you have your module in a place with low signal strenght. Does your module offer an u.fl connector for a better antenna?

Answer 2

Don't know why, I had to manually set the DNS t0 8.8.8.8 using AT+CDNSCFG?

It had DNS entries in there but they didn't want to resolve for some reason.