.NET Core SignalR, Server timeoute / Reconnect issue

Configuring automatic reconnects only requires a call to withAutomaticReconnect on the HubConnectionBuilder. Here is what my JavaScript code looks like for configuring my connection:

connection = new signalR.HubConnectionBuilder()
.withUrl("/publish-document-job-progress")
.withAutomaticReconnect()
.configureLogging(signalR.LogLevel.Information)
.build();

You can configure the backoff period by passing an array of retry delays to the call to withAutomaticReconnect(). The default for this is [0, 2000, 10000, 30000, null]. The null value tells SignalR to stop trying. So, for example, if I wanted it to retry at 0, 1 second and 5 seconds, I can configure my HubConnectionBuilder as follows:

connection = new signalR.HubConnectionBuilder()
.withUrl("/publish-document-job-progress")
.withAutomaticReconnect([0, 1000, 5000, null])
.configureLogging(signalR.LogLevel.Information)
.build();

I have the same issue (Question 1), and i resolve with this:

const connection = new SignalR.HubConnectionBuilder()
    .withUrl("/hub")
    .configureLogging(SignalR.LogLevel.Information)
    .build();

connect(connection);

async function connect(conn){
    conn.start().catch( e => {
        sleep(5000);
        console.log("Reconnecting Socket");
        connect(conn);  
    }
    )
}

connection.onclose(function (e) {
            connect(connection);
    });

  async function sleep(msec) {
  return new Promise(resolve => setTimeout(resolve, msec));
}

Every 5 seconds tries to reconnect, but i don't know if this is the right way to do this.

ASP.NET Core 2.1 (current LTS release) with the corresponding SignalR release doesn't seem to have some integrated reconnecting method avaliable. The code from @Shidarg doesn't work for me, it calls the reconnect method in a infinitive loop crashiny my browser. I also like the async/await syntax from C# more, so I updated it:

let reconnectWaitTime = 5000
let paramStr = '?myCustomArg=true'
let client = new signalR.HubConnectionBuilder()
    .withUrl("/overviewHub" + paramStr)
    .build();

client.onclose(async () => {
    console.warn(`WS connection closed, try reconnecting with loop interval ${reconnectWaitTime}`)
    tryReconnect(client)
})
await tryReconnect(client)

async function tryReconnect(client) {
    try {
        let started = await client.start()
        console.log('WS client connected!')

        // Here i'm initializing my services, e.g. fetch history of a chat when connection got established

        return started;
    } catch (e) {
        await new Promise(resolve => setTimeout(resolve, reconnectWaitTime));
        return await tryReconnect(client)
    }
}

But for ASP.NET Core 3 they included a reconnecting method:

let client = new signalR.HubConnectionBuilder()
    .withUrl("/myHub")
    .withAutomaticReconnect()
    .configureLogging(signalR.LogLevel.Information)
    .build();

Per default it try three reconnects: First after 2 seconds, second after 10 seconds and the last about 30 seconds. This could be modificated by passing the intervalls as array parameter:

.withAutomaticReconnect([5000, 1500, 50000, null])

This example re-trys after 5s, 15s and 50s. The last null param tell SignalR to stop re-trying. More information could be found here: https://www.jerriepelser.com/blog/automatic-reconnects-signalr/