Pretty much nothing worked for me, so I threw myself on the mercy of the server admin guy.
I’m not sure what he did… apparently he auto-updated SuSE, installed all updates and rebooted the server.
Magically this resolved all my issues, but you know admins, who knows what else he might have had a fiddle with.
But the bottom line, which may or may not be good news for you, is that it was something server-side that needed changing.