I’m trying to cast movies from my laptop’s disk to a Chromecast device and on my smartphone in the MX Player app. Of course, all devices are on the same home network. Previously, I used the Archer C7 router and everything worked. Now I can’t cast using the MR500 router. Maybe something is blocked in the router settings?

Here are the confirmed working configuration for the SMB network access for MX Player:
Name : Anything
Server : smb://HostName (example : smb://mypcname)
Path : Movie (Only the name of shared folder name)
Uncheck Anonymously
Domain : nothing/empty
Name : Your-PC-User-Account-Name
Password : The-Password