This behavior sounds exactly like that reported in bug #1229195. Can you update to openconnect 5.02-1 that was just uploaded yesterday and see if this version fixes the problem for you without the need for the --no-xmlpost option?
This behavior sounds exactly like that reported in bug #1229195. Can you update to openconnect 5.02-1 that was just uploaded yesterday and see if this version fixes the problem for you without the need for the --no-xmlpost option?