Thanks, just reinstalled my YunoHost instance to fresh 4.0.8.3 and encountered the issue.
Fixed it with your solution, though not limitating it to eth0:
mkdir -p /etc/yunohost/hooks.d/post_iptable_rules/
echo "iptables -A INPUT -p udp --sport 1900 -j ACCEPT" \
> /etc/yunohost/hooks.d/post_iptable_rules/001-fix-upnp
yunohost firewall reload
yunohost firewall upnp enable