I also have a question: how to make sure my ip address is correct. I directly use the ip and mac shown on the internet setting.
what Internet settings? of your computer?how is the Ethernet module connected to network? to router or to computer?use DHCP. (Ethernet.begin(mac)
Yes, the Internet setting is about my computer. After I check the mac and IP of my computer, I unplug the net cable and connect it to the Ethernet module. So I think all the thing would be same.By the way, if I use Ethernet.begin(mac), Ethernet.localIP() will return the same IP as the IP I see in the Network Center of my computer.