Every GameServer can handel 50k spawn objects, So your only way to fix that (on 1 gameserver) to make less spawn of mobs, Use this query
PHP Code:
USE [SRO_VT_SHARD]
GO
UPDATE dbo.Tab_RefNest SET dwmaxtotalcount=3
Change SRO_VT_SHARD to your shard db name ,
Beside this query don't make big spawn change as u will find mobs spawn number is oky (or better) .