hi federicofor the RJ45 in wruth , you can use 10/100BASE-T series, for which to use is based on your application. for LAN8742A-CZ-TR, the LAN8742AI-CZ-TR is also can be used in the system.
can you try LAN8742A-CZ, the AI-CZ is for the industry version which have the wider temperture -40 to +85 degree. the A-CZ have 0-70 degree temperatue. in Mouser it have stock for the two chips in stock.