Is it working ok now? There was some maintenance performed on the Sat night which was in the same datacentre as the server, so I wonder if it's related to that:
SoftLayer Engineers will be performing emergency maintenance on DAR01.SR01.DAL01 in an effort to correct intermittent latency / packetloss issues. For the duration of the maintenance, traffic flowing through DAR01.SR01.DAL01 will be redirected through DAR02.SR01.DAL01.
Customers can expect to see latency / packetloss as routes reconverge across redundant routers on both the public and private networks. While the maintenance window is set for 2 hours, we expect the maintenance to take no longer than 20 minutes while the router reloads.