socket.io buffered messages loss after reconnection

[tianhuat]

This is on client side

socket.on('connect', () => {
    console.log('client connect', socket.id);
    const token = getToken();

    socket.emit('token', token);
});

socket.on('message', data => {
         ....
        //handle message
    });

This is on server side

        io.on('connection', (client) => {
            client.on('token', token => {
                verifyToken(token)
                    .then(({ _id: clientId }) => {
                        if (!clientId) return;

                        if (!connections[clientId]) {
                            connections[clientId] = new Map();
                        }
                        connections[clientId].set(client, 1);

                        client.on('disconnect', () => {
                            connections[clientId].delete(client);
                        });
                    });
            });
        });
    }

    async sendMessageToClients (workspaceId, message) {
        const workspace = await getWorkspaceQuery(workspaceId);
        if (!workspace) return;
        const workspaceMembers = workspace.members.map(({ user }) => user);
        for (const memberId of workspaceMembers) {
            if (connections[memberId]) {
                for (const clientConnection of connections[memberId].keys()) {
                    console.log('send to client', memberId, message.content, clientConnection.connected, clientConnection.id);
                    clientConnection.emit('message', message); 
                }
            }
        }
    };
}

I purposely make a client offline by disconnect the wifi connection (make it in offline mode), what happen is that

a. if the disconnection is short, socket.id stay the same and I can get the buffered message send by other client when comes online;

b. but if I the disconnection is longer, the socket.id will change, and I can't get the buffered message send by other client when comes online.

How should I address that?

Since according to here the messages should be ideally buffered after reconnection.