What error message did you receive?
Were you able to detect the WiFi network of your Sagemcom modem/router?
If yes, when you tried to connect to it, what happened?
Please provide more information for us to assess your issue.
it gets connected with the internet, i was able to set it up but when i try to cast; it says Network error; try connecting again, did same process multiple times was unable to.
My computer (MAC M1) browser (chrome) does not detect device at all.
Just to confirm, is the internet working using your TPG 5G broadband service?
Have you contacted Google support to check your Chromecast? If yes, what did they advise?
What troubleshooting have you tried so far?