Synchronizing the calendar and contacts with NextCloud on Android is fairly straight-forward. It will require both the Android NextCloud client and an app called DAVx5DAVx⁵.
Once set up, the synchronization of the calendar (and optionally contacts) will be automatic and will not require any further calibration by the user. Any changes made from the client or the server will be synchronized automatically.
Note: A NextCloud account is required to progress with this tutorial. If you do not have an account, please provide an e-mail address and your desired username to a system administrator.
Instructions
Installing the Required Apps
Install and Sign Into the NextCloud Client
Navigate to the Google Play Store and search for the NextCloud Android client. Once installed, the app will prompt the user for access to their NextCloud account. Sign-in with your NextCloud credentials and grant access to the Android app.
Once installed, run the application and enter the server address:
https://cloud.grey.fail
The user will then be directed to the default browser where login credentials can be entered and the Client can be granted access to the user's account:
Once access has been granted, the browser can be closed. Congrats! We've connected our Android client to our NextCloud account. Now that the account is connected to the NextCloud server, we're ready to install DAVx5DAVx⁵.
Install DAVx5
Navigate to the Google Play Store and search for and install DAVx5.
Link the NextCloud with DAVx5
Once installed, navigate back to the NextCloud client. Within the client select the (hamburger style) menu button located in the upper left. Then select "Settings."
From the settings page, select "Sync calendar & contacts."
DavX5DAVx⁵ will open. There the user will again be prompted to log-in and grant account access to DavXDAVx⁵5
Once access has been provided, the user will then have the ability to select what calendars and contacts to synchronize with their device.
Conclusion
That's it! Congratulations on linking your Android device to a NextCloud shared calendar. Any changes made to the calendar on the device, from another calendar application, or in the NextCloud GUI will synchronize across all linked devices.