Hi,
Assuming you use RUTX50 to provide internet connectivity and you would like to setup a mesh network to expand Wi-Fi coverage, then you need another device to act as a mesh node.
RUTX10 would probably be the best option here. RUTX10 does not have mobile connectivity option, but it supports 802.11b/g/n/ac Wave 2 (WiFi 5) with data transmission rates up to 867 Mbps (Dual Band, MU-MIMO). In this case, RUTX50 would be the mesh gateway and RUTX10 a mesh node. It is likely that 802.11ac Wi-Fi will be enough in your case, but this depends on your requirements. Currently, none of the Teltonika devices support 802.11ax wireless standard.
Kind Regards,
Andzej