Im curious now if its just your router thats causing issues now. Do you know someone else with a different router that maybe you could test with?
The modem may be lit up but could be maybe the network thats caysing the actual error. You might ask Kazade how view the debug output. I cant remember the command for it off the top of my head.
If your new modem doesnt work thats my next guess since your setup did work before... Wonder if some how your router is blocking internet connections through your raspberry pi?