I have been using an old Android phone for a while now to push data from a remote location (my boat) to my server. Over HTTP it works fine, but I can’t get it to work with a self signed SSL certificate. Is it true that the HTTP POST will fail on a self signed certificate?
I’m not familiar with Android https implementation details, but I would guess a self-signed certificate is a no-go. Can you use Let’s Encrypt on your server to get a free, trusted certificate?
I have a signed certificate now and the app POSTs fine again. Conclusion: self signed certificate does not suffice.