Hi,
It is seen from your log-file, that your receiver has sent requests to the server 2 times, but there was no response.
Possible reasons:
1) request from receiver has not reached the server (internet problems, overloaded upload, for example - you may use torrent client and your uplink is busy so that your receiver cannot even send request);
2) timeout value is too low. Try to increase it somehow.
UPC package is not overloaded, we have reserve. This is proved by responses in your log-file - 600-700ms. If the cards were overloaded, responses would be higher. By the way, UPC works well enough even with 3500ms responses.
One more thing - nobody on the forum but you complain on UPC. It means that the reason is 99% not ours.
Regards