The Second Life server code upgrade went badly yesterday, causing significant concurrency drops around peak hours. The upgrades will continue today with rolling restarts of most regions. The Support portal was unavailable during some of the time as well.
Statistics compared with Tuesday, January 22nd:
Peak concurrency dropped 1031 users, a decrease of 1.79%.
Minimum concurrency grew 56 users, a tiny of increase of 0.18%.
Median concurrency dropped 984 users, a decrease of 2.23%.