SA Server Error, RegServerRcv_RegisterServerResult failed, reason = 21

[F_UKT_Free_Kill]

Just out of the blue, for the last week now, when I try to start up our SA server, I get the following error:

callback: RegServerRcv_RegisterServerResult failed, reason = 21

Does anyone have any idea what could be causing this or what reason 21 is?

[F_UKT_Free_Kill]

Just out of the blue, for the last week now, when I try to start up our SA server, I get the following error:

callback: RegServerRcv_RegisterServerResult failed, reason = 21

Does anyone have any idea what could be causing this or what reason 21 is?

[Wranglersm]

I'm getting the same error, I hope someone else can figure this out