+**Important compatibility information:**
+If older Fhem-versions (before 2015-06-19) or [Homegear][] before 2015-07-01
+is used to connect to hmland, the `-I` switch might be needed to
+impersonate a LAN-interface (this replaces the identity string HM-USB-IF with
+HM-LAN-IF). eQ-3 rfd (CCU and configuration software) works without this switch.
+Software which needs this will not keep a stable connection open to
+hmland without this switch. It was the hardcoded default in versions
+< 0.100.
+
+This incompatibility is needed so connecting software is able to
+differentiate between HM-CFG-LAN and HM-CFG-USB.
+
+[releases-directory]: https://git.zerfleddert.de/hmcfgusb/releases/