On installation, FEAT VPN asks for five permissions. Here's what they are and why FEAT VPN requires them:
INTERNET, which enables network communication. We use this permission to establish the L2TP connection with the built-in L2TP client as well as the OpenVPN tunnel with the remote OpenVPN server.
RECEIVE_BOOT_COMPLETED, which allows an app to detect when the Android device was switched on or rebooted. We need this permission, because FEAT VPN can be configured to automatically start on boot.
WAKE_LOCK, which allows an app to prevent the device from sleeping. FEAT VPN uses this permission to prevent the device from turning off the screen when running automated tests. See the section Initial FEAT VPN Setup for details on these tests.
READ_LOGS, which allows an app to access the Android system log. We use this permission to read the system log entries of the built-in L2TP client. If you report a problem with FEAT VPN, we ask you to send us the FEAT VPN log, which also contains said system log entries. This helps us to track down the problem.
WRITE_EXTERNAL_STORAGE, which allows an app to write to the SD card. When you send us the FEAT VPN log, it is compressed with gzip and then attached to an automatically generated email. The compressed log is written to the SD card and later deleted. This is why we need this permission.
When FEAT VPN is started, it goes through a few basic checks to make sure that it works as intended on your device. Here are the things that can come up at this point:
Duplicate Installation. If you are upgrading from FEAT VPN Lite to the commercial version, it is best to uninstall FEAT VPN Lite first. FEAT VPN Lite and the commercial version cannot coexist on the same device. If you start FEAT VPN and it indicates that both versions are installed, please uninstall FEAT VPN Lite. Then start the commercial version again.
Crash. If you restart the FEAT VPN app after it crashed, it asks you to send us the FEAT VPN log. Please do not ignore this. Please send us the log. It helps us to make FEAT VPN more robust.
Device Problems. A tiny number of devices comes with a broken L2TP implementation in the built-in L2TP client. Here are the problems that are detected by FEAT VPN at startup and their associated error codes:
But before you try to work around this problem, find out whether it really affects you. Technically, the problem behind this error code is that on some devices TCP-based DNS lookups may fail. The vast majority of DNS lookups, however, is UDP-based. DNS uses TCP only for large DNS responses of 512 bytes and more and domains with DNS responses that large are very rare. So, simply go ahead and surf a little with an established VPN tunnel. If you encounter problems with DNS, i.e., if your browser tells you that a certain website cannot be found, then try to work around the problem. If this does not help, then please let us know in our support forum. Also, your device vendor may be offering an upgrade to a newer Android version that adds support for IPv6 and makes this problem go away.
Turn off any of the above components that you do not absolutely need. Then restart your device. Now the disabled components do not store any settings in the system property table of your device, leaving space for the settings of the built-in L2TP client. When you now start FEAT VPN, this error code should not appear again. If it does, then please let us know in our support forum. Also, your device vendor may be offering an upgrade to a newer Android version that increases the size of the system property table and makes this problem go away.