Up to now the latest R356 is still running with upnp disabled.
Please bear in mind, that upnp has been working w/o problems in R336 - at least I did not detect any and I am pretty sure it was running for days. I can retest that in parallel if it would help you.
Let's keep fingers crossed that HG ist still alive this afternoon.
Something else in this build, occasionally the icons do no refresh, e.g. manual trigger on shutter to be up and shutter (x10) goes up but icon still shows shutter to be down. Even if you reload the page it stays down. Same happens to x10 light bulbs.
Cheers
Jens