I'm pretty sure that the default IP address for the 220v is also
http://192.168.1.1
Can you still
ping the router on 192.168.1.1 ok to check?
If you can ping it ok but just cant get to the web interface it could just be a bit "confuddled". Ive had this happen on my Voyager(2100) a couple of times in the 2+years Ive had it.
Rebooting the router normally seems to do the trick.
Since it otherwise seems to be working ok and in view of your concerns over the speed drop then it should be ok to leave it, but it just means that you wont be able to view any router/line info.
If you contact BT support the first thing theyd likely tell you to do is reboot the router.