Here is what I am told concerning EBay.
Gavelsnipe is in the process of moving to a multi-IP solution so that eBay will be less likely to block bidders. Gavelsnipe currently snipes from one server with one IP. If there’s too much traffic to eBay from that server, so they started blocking logins for a period of time.
Most of the issues have gone away with current setup.
Looks like looks like 3 out of 662 bids missed last week due to the issue – so that is 99.5% success rate.