Make sure you also pay attention to the distance rating of the SFP. I had a very similar experience with modules not working at the right speed sometimes. Turned out I was running 50 meters of cable over a 30 meter SFP. Got the correct one, and as low wattage rating as possible and it's been rock solid ever since.
oh yea! great point, I forgot about that. I am using PiAware to handle the decoding so I do have an Enterprise Account. I will have to check if I can make API calls for free.
Unfortunately FlightAware Enterprise doesn't get discounted API access.
The FlightAware API I was using (they have multiple) didn't provide all the data I wanted either. The ADSB Exchange Rapid API was more comprehensive, but came at a cost.
The aircraft don't broadcast everything over ADSB - so these sites are all pulling from a database somewhere else. It appears ADSB Exchange and some of the pi based UIs use the tar1090-db. This was easy to work with and free - just need to update it periodically due to registration changes.