If the restaurant is interested in acquiring a thermal printer, it is recommended to check the following LAN printers from Star which are quite reliable and easy to install:
Star TSP143IIILAN Ethernet - Connection to the router via Ethernet cable
Star TSP143IIIWLAN Wireless LAN - Connection to the router via WIFI
If the printers above seem too costly, then a less expensive option would be the following model from Epson:
Epson TM-T20III - Ethernet - Connection to the router via Ethernet cable.