RCM4200 - IP information

Hi, Does anyone had the problem that the IP adres changes or not changes after repower of the RCM4200. I have conected a LCD to the unit which shows the IP, but sometimes it differs from the actual IP adres. So the DHCP gives a new actual IP, but somehow the previous IP stays in memory of the RCM4200 which is shown by the LCD. It differs on what kind of network the unit is connected to. Probably I need to change something to prevent that the unit is not having this problem depending on the kind of network. Please help me out. Thx

Some extra info which might help.
The problem occures when the network stays connected ad repowering. When netwerk is disconnected and connected after repower. the problem does not occure.