LDS can't find my machine over Wi-Fi after a router change

The machine is still trying to join your old SSID. Two things to check, in this order:

1. 2.4GHz. These machines are 2.4GHz only. Lots of new routers ship with band steering and one combined SSID — the machine sees a 5GHz-only beacon and gives up. Either split the bands into separate SSIDs or temporarily disable 5GHz while you configure.
2. Re-run Wi-Fi configuration over USB. Connect by cable, go into the network settings in LDS and push the new SSID and password. The machine won't re-scan and guess.

Also worth knowing: if your new router has client isolation / AP isolation on (common on ISP boxes), your computer and the machine can both be online but unable to see each other. Turn that off for your network.