wow, Wow, WOW ... time travel is for real!!!  

It’s certainly possible the CR200 has given up the ghost. You might try (never had one, not sure if it is possible) removing the battery, and re-seating it.
 

If memory serves (these have been unsupported for quite a while), these operate via SonosNet, and not via WiFi, so one SonosNet capable speaker must be plugged in to an Ethernet cable. 

Oops. Missed the removing the battery statement, sorry. You still might want to be sure your system is on SonosNet, but it is definitely possible this is (to quote Monty Python) a dead parrot. 

August 8, 2024, Germany.

Same issue here. Cotroller CR200 not working anymore.

It says on the display that the network-configuration had changed and one should contact a website for further information, however that website is not available.

I tend to be of the opinion that this is another try by Sonos to get rid of the Controller CR200, which still worked wonderfully, not like the fusion of controller S1 and S1 did. 

It seems to me that there is a plan to press customers step by step to get rid of their old devices of the Sonos product family and buy new gadgets.

However, dear Management of Sonos, it is not appropriate and it is not sustainable to trash such a - not really cheap - item, that has no techical fault. Brigandage?

I wonder what could have changed? The last update to S1 was in April.

Mind you I’m just impressed there are any CR200s that still have working touchscreens.

I take it you are still using S1 and not updated to S2 by mistake?

Re-added my Bridge and was able to get the CR200 connected. Using my system in S1 mode.

When I had a CR200 (a couple of years ago now) the only way I could get it to connect to my (then) S1 system was to start the system config with a Bridge, and build from there. If I tried any other device than a Bridge I simply could not get it to work.

When I sold it, I bundled it with an old Bridge so that the new owner would be able to get it up and running.