The customer is most likely restricted due to high usage. You can diagnose the problem by running:
lveinfo --period=1d --by-fault=mep --display-username
If a user is limited to max entry processes, you will see how many times his site was limited (served 508) within past day (--period=1d). You can also monitor current usage via:
In most cases, you don't want to do anything, as this customer might overload the system by exhausting all Apache connections or some other resources of the system. Yet, in some cases you might want to increase the limit by doing:
lvectl set USER_ID --maxEntryProcs=NEW_LIMIT --save
The default limit is 20 concurrent connections (max entry processes).