Fixing sent and received signal is good but no internet

This is probably one in a thousand case - where there is internet signal sending and receiving can be seen on the status. However there is no internet at all. Why? Checked everything including on desktop internet troubleshooting and modem reset won't fix it. Until i got into a point assuming the Modem was faulty - but after changing Modem it's still no internet connection. So...i am just trying my luck take a look into the socket of the LAN line and found there was a loose cable. Just screwed it back and test the old modem..it works!!. I have brought back the old modem to life...not the thunderous lighting that i thought was killing it.