Because it is made inappropriate public security key by some users, to stop the operation of the SSID “utroam” of the web authentication method in 4/28 (Thursday) 17:00. utroam user please do the transition to an SSID “utroam-1x” so far.

utroam-1x user is not required configuration changes. It should be noted that the change of the reissue and the connection settings associated with it of utroam account, please go as usual until 4/30.

Further information is below.
http://www.u-tokyo.ac.jp/ja/administration/dics/service/utroam.html (Japanese)
http://utroam.nc.u-tokyo.ac.jp/ (oncampus access only)