Failed to connect to :<PORT>: [Errno 111] Connection refused

[CallumWalley]

Seems to happen to about 1 in 20 attempts to connect.

From user with this issue.

[I 2023-09-26 14:11:39.408 SingleUserLabApp log:189] 101 GET /user/*/vdt/vnc.html (@::ffff:130.195.253.20) 1.65ms
[I 2023-09-26 14:11:39.408 SingleUserLabApp handlers:447] Trying to establish websocket connection to ws://localhost:60075/vnc.html
[I 2023-09-26 14:11:39.419 SingleUserLabApp handlers:454] Websocket connection established to ws://localhost:60075/vnc.html
127.0.0.1 - - [26/Sep/2023 14:11:39] 127.0.0.1: Plain non-SSL (ws://) WebSocket connection
127.0.0.1 - - [26/Sep/2023 14:11:39] 127.0.0.1: Path: '/vnc.html'
127.0.0.1 - - [26/Sep/2023 14:11:39] connecting to: :43889
127.0.0.1 - - [26/Sep/2023 14:11:39] Failed to connect to :43889: [Errno 111] Connection refused

Problem is fixed with a jupyter session restart.