Linux (CentOS; RedHat) -Error when turning on the node in Mode-2 (hyper_server) . Error 503

[Skyp]

Hi, I wrote the instructions and within the framework of it I conducted testing on disabling the working node - receiving all sessions on the server (master) and enabling the working node.
The status of the node(VM) is updated to Active when enabled, but users whom the master should send to this node receive error 503. (Below I have described the Step-by-step sequence of steps)

Step 1: 

Step 2:

Step 3 (As if the node is out of order - fine): 

Step 4 (I opened a large number of sessions and the master took them all on himself - that's fine): 

 

Step 5 (I started the node😞

Step 6(the master's node status has changed to online - that's fine) :

Step 7 (I'm trying to open the interface (from Master)):

 

I specially reproduced this situation separately and attached Hyper_server logs. I ask for help how to exclude a situation when lifting the server (without restarting the Master) drops the work of a part of the cluster? 

If, after enabling Node(Service/VM) (step 6), I restart and destroy all threads on the master, then the child node will work correctly and there will be no error 503 - but for this I will have to disconnect all users from the master:

Do you have any idea why this is happening?

Version: 1.90.0.1564

Logs.zip