You can do MAC-based filtering using firewall rules. But only for IPs, so you need to pre-determine the relevant IPs, or re-evaluate them regularly, because for facebook, google etc. they change on regular basis.
The real method to do MAC-based filtering, taking into consideration domain names, is the usage of a proxy, i.g. squid proxy, running on the RUT955.
All this can be much easier be implemented on a RUT955, running official openwrt, instead of Teltonikas stuff.