So my router is havng problems and i have a modem/router from my old isp. I tried to hook it up and there was no internet. What did i do wrong? Everything was plugged in and turned on.  The wifi was working but the internet light wasnt solid so there was no actual internet connection through the modem.Assuming the modem is compatible with your new ISP's system, they NEED to enter and authorize the MAC address of the modem.i don't know too much about internet stuff but i FOUND with this problem if the email the ISP gives you is locked into the modem you can't change it. for example [email protected], if the "optusnet.com" bit is greyed out(doesn't let you change it) and not changeable, no you cant use it with a new ISPhuh? You can use any email address with any modem.my old modem was locked to optus. So it had optusnet.com locked in so all you could change was the user name but not the IPS name. so for example [email protected], the modem would only let you change someone123 but it would not let you change the optusnet.com bit.You can access any and all email accounts from any modem. Let's move on.