I was able to accept payments, but now the Pay button does not pop me out to PayPal. It merely keeps retrying to connect to PayPal, several times a second, as the log shows. I have made no changes on the website.
The code is unaltered, except for modifying the donation levels. I tried uninstalling and removing all records from the database, then reinstalling, but that did not help.
The strangest part of this, which I hope will give you a clue to what's going on, is that I have tried several machines on various networks and all but one fail. -> From exactly one machine I have successfully hit the PayPal landing page. And when I spoke to PayPal their tech was also successful.