Hi guys
This is my first time writing to this forum.
My 1st Gen Chromecast was working well with my old router TP-Link TL-WR1043ND.
Recently Telekom upgraded my router with a D-Link DIR-842 Router and Chromecast cannot be setup anymore.
The problems I faced was (1) cannot detect my SSID (2) I turned off 5GHz wifi band but also cannot connect.
Anybody with similar issues and have a solution?
Very much appreciated for any kind assistance!

Have u tried to update and/or reset the chromecast?

Yes - many many times and for many days -

Try go through the setup using your phone again..
And also possible to use 2.4Ghz wifi channel under 1-10 only
Simple SSID, without fancy symbol

TM has assigned a suffix for my SSID@unifi - how to get rid of the @unifi?