I've seen a couple variations on this problem described here on the forums, but they're scattered around threads that are about different topics.

PROBLEM:
My GDI-IRD4400m can connect to my wireless network and play music just fine for a while - a couple hours. But then it stops playing and hangs forever while it tries to reconnect. If it was playing an internet radio station, it says "stream ended" and "connecting". If it was playing music from my local collection, it says "connecting" for a few seconds for each song in the playlist and then gives up and moves on to the next track.

Even if the radio is in "standby" mode, using the on/off button on the front of the radio, it eventually loses its connection. For example, I can listen to the radio for 15 minutes in the morning, and then put it in standby. When I come back later in the day, it can't connect to anything.

Once it's in this failed-connection state, if I try to switch to a different station, it hangs on "updating station list from Reciva". If I try to choose new local music to play, it tells me it can't find any UPnP servers.

When it gets into this state, nothing helps except for powering the device down, using the power rocker switch in the back of the radio. Once I power it down and back up again, it can connect to everything just fine.

MY SOLUTION:
What finally fixed the problem for me was changing a setting on my wireless router. My router had a mode called "Super-G" turned on, by default. Turning that off fixed my internet radio troubles. Apparently super-G mode is a non-standard extension to the wireless-G protocol that a lot of routers support.

In my case, my router is a D-Link DGL-4300. You can usually get to the settings from a web browser on a computer with a wired connection to the router by entering the address http://192.168.0.1/ in the address bar. After signing in with the proper password, go to
Basic->Wireless Settings, and look for "Super G™ Mode". Set it to disabled.

I can't guarantee this will help, but it worked for me. Good luck!