How to make a backup local port on Microtik (RSTP doesn't help)?

Question

Computer networks

Please tell me how to set up a local network in this way:
GIVEN:

• first Mikrotik router
  
• second Mikrotik router
  
• managed switch (D-Link DES-3200-28P)
  
• all three are connected in a ring in this way: the first router - 1Gbps - the second router - 1Gbps - D-Link - 10Mbps - the first router
  

NEED:

1. if the first router can communicate with D-Link through the second router, then let everything work through the second router (i.e.: the first router - 1Gbps - the second router - 1Gbps - D-Link)
   
2. and if not, then let it switch to the alternate slow path (i.e.: D-Link - 10Mbps - the first router) until the main / fast one works
   

Now bride RSTP is enabled everywhere , but the problem is that the first router is constantly working along the slow path, and not along the fast one ...

Answer 1

Set up RSTP.
Root-bridge must be at Dlink
The first Mikrotik has a link weight towards Dlink that must be greater than the weight on the way towards the second Mikrotik
https://wiki.mikrotik.com/wiki/Manual:Spanning_Tre...