Thank you for reporting the bug. If this happens again next time, would you send us a feedback message from within the NextD Remote app (through the Support & Feedback function inside the drop down menu) so that can take a look at the error log that is automatically attached?
We don't believe you need to reinstall the NextD Remote app to fix the connection. Next time it happens, would you try rebooting your WiFi router instead? We have a solution article that could be helpful to you: