If I try to configure Static DHCP Leases from GUI on RUT955, it forbids me to write some characters on hostnames that are correct on any other DHCP server. It also do not tell what characters are not permitted.

As far as I have seen, it does not permit characters '-' and '.' which forbids entering the domain name on the hostsnames.
If I edit manually the file /etc/config/dhcp and put the hostnames with all the characters and domain, they are perfectly accepted.
On any other OpenWrt router I have they are accepted normally, so I don't know why of this restriction.
Will it be fixed on any future firmware?
Beside the above "problem". I cannot see the static leases given anywhere on GUI. Is there a way of seeing them as on any Openwrt version? The only way right now is reading the current /var/dhcp.leases file which I consider rather inconvenient.
Sorry. I found them on Status -> Network -> LAN