Hi,
This is something that gets asked often and there are ton’s of reasons for this.
The comparison to CloudFlare makes sense as they are counting something quite different (assuming you use js tracking). While they count the http requests, you count the people who execute Javascript and are not in Matomo’s Bot user agent list.
But there are stil reasons why there can be too little visits counted (see also here)
- the user was using an adblocker that blocked Matomo
- the user has disabled JS or blocked all third party scripts
- the user has enabled DoNotTrack and therefore their visit isn’t tracked by Matomo by default
- this is the most likely source for a difference as GA ignores DoNotTrack
- the user has used the OptOut iFrame to OptOut of tracking and is therefore not tracked.
- There is an error with your webserver causing some requests to be dropped (e.g. by using mod_security)
- it is definitly possible that there is something wrong with your Webserver config that causes a small portion of requests to fail to reach Matomo.
- for HTTPS you could check your Matomo domain at https://www.ssllabs.com/ to see if the SSL-Config is correct
- There was an PHP error when the data should have been stored.
- While this is a bit unlikely, it isn’t impossible.