Next time you get the ‘authentication’ screen… try ignore the top part (“request”) and just do the addition part at the bottom and push that button. That works for me. It seems to be protection from ‘non-trusted’ internet sources. They must have a reference list of spammers and ‘suspect’ sources. One of these is the TOR network that I use for anonymity. If I post from an ‘open’ ISP, I need no authentication. When I post from TOR network, I get the authentication at log-in. (I log in every time… I do not stay logged in.)
So I suspect that the anti-spam guardians at the gate do not like your satellite ISP for some reason…
I have found that rarely, if I take a long time to compose a post, or linger on that page with no action, it will ask me to authenticate again when I hit the ‘publish’ button. So there seems to be a ‘timeout’ function on the authentication also.
Try just doing the math portion at the bottom to authenticate… it’s quicker.