well that explains it... its targeting your Mongo docker internal IP on port 27017 and there is nothing there. This could mean 2 things. That RC is not mapped correctly to mongo container using the "Links" tab, or that mongo db is not running as it should.
Can you use your computer and try a telnet command:
telnet 192.168.86.25 27017
? If you get a black screen then mongo is running on that port on your NAS. If that is the case then we are back to the problems that I just wrote about.
Double check that mongodb is running, and try and reconfigure again your RC container with "links" options to mongo container.
If nothing else works, change RC variables (mongo_url and mongo_oplog_url) and instead of mongodb://root:[email protected]
:27017/db?authSource=admin set it as mongodb://root:[email protected]