How to forward media server from provider router to clients of Mikrotik device?

RouterOS Beginner Basics
9

I guess that what originated the misunderstanding is that the Fritzbox uses something called UPnP AV (Universal Plug and Play Audio/Video, which is NOT "plain" UPnP, but rather an extension of it):
https://en.wikipedia.org/wiki/Universal_Plug_and_Play#AV_standards

The whole stuff is documented/(sort of) standardized by DLNA (but Fritzbox claims compatibility to it without having actually been certified):
https://fritz.com/en-it/apps/knowledge-base/FRITZ-Box-7590/279_DLNA-and-the-FRITZ-Box-Media-Server

It seems like some special configuration is needed to allow the packets/discovery/whatever to pass through:

though I couldn't find anything confirmed about this stuff.

There is a (as usual telegraphic) article on Mikrotik help about Ros being able to do the same (DLNA) media server but nothing about the needed settings on other devices on the network:

The thing revolves around SSDP, so maybe, just maybe, there could be something useful here: