We recommend to use chromecast over DLNA casting to your tv but still it may happen that casting will not work properly. There are several reasons why this happens.
Stremio does not provide any content and everything is provided by add-ons. That mean we are not able to control format of the provided movies and there are multiple formats like avi, mp4, mvk and others. Chromecast support only some of these formats therefore casting not supported formats requires converting movies to the supported format that takes a lot of processor power. It might happen that we don't support converting some of the formats so you will not be able to play the video over chromecast or there will be no sound.
If you have problem with discovering Chromecast please take a look on the following links: