When you run the web connector, it sends items to Connex to sync. Connex holds them in its database and syncs 200 items per hour. When more than 2400 items are queued, Connex says wait until more items are processed.
We implemented this safety lock to ensure several thousand items failed to queue, due to a settings issue.
If your web connector is on auto-run, set the interval to 30 - 60 minutes. If you run the web connector every minute, this can cause too many items to get queued up.
On the inventory tab of the Connex configure page, select the timezone where your QB is located. If it is running on a remote machine, it's probably EST or UTC time.