Hi rexysandin,
You've done some good troubleshooting already! If you are still having trouble with an accessory on your iPhone, we'd like to have you try the steps listed in the resource below that can help with isolating this issue a little further
If you see an ‘Accessory may not be supported’ alert:
"1. Update to the latest version of iOS
Some accessories might require the latest version of iOS. Make sure that you update to the latest version of iOS.
2. Make sure the accessory is compatible
If this is the first time that you tried to use the accessory, make sure that it works with your device. Some accessories only work with certain models of iPhone, iPad, or iPod touch. If you aren’t sure, contact the manufacturer.
3. Check the connections
Disconnect and reconnect the accessory to see if the alert goes away. If it continues to appear, check the connectors on the accessory and your device for damage or debris. If necessary, gently remove the debris and clean the connectors on your device.
If you see this alert and don’t have any accessories connected, contact Apple Support."
Take care.