No reaction after timeout period has passed

First of all: Thanks for writing a library that works with an FTP server and is easy to use!

I created a new app in Xcode 10 with Swift 5 and the latest version of BlueSocket (installed via CocoaPod) to test it and I've come across a problem:

If I try to write a command like mysocket.write(from: "LIST\r\n"), mysocket.readString() never returns anything, even after the timeout period has passed.

My code (you can find a list of return codes here.):

private let url = "speedtest.tele2.net" //This is an open FTP server that can be used for testing
private let port:Int32 = 21
private let username:String = "anonymous"
private let password:String = ""

@IBAction func buttonClicked(_ sender: Any) {
    do {
        let s = try Socket.create()
        try s.connect(to: url, port: port, timeout: 10000, familyOnly: false) //10secs

        if s.isConnected {
            var answer = try s.readString()

            if answer!.hasPrefix("220") { //220 Enter username
                try s.write(from: "USER \(username)\r\n")
                answer = try s.readString()

                if answer!.hasPrefix("331") { //331 Enter password
                    try s.write(from: "PASS \(password)\r\n")
                    answer = try s.readString()

                    if answer!.hasPrefix("230") { //230 User logged in
                        //If I use "LIST" or "NLST" with the first socket, it tells me: "425 Use PORT or PASV first" ("PWD" works), that's why I'm opening a second socket, just for data:
                        try s.write(from: "PASV\r\n")
                        answer = try s.readString()

                        if answer!.hasPrefix("227") { //E.g. 227 Entering Passive Mode (90,130,70,73,100,187).
                            let new = getNewIP(answer!) //returns e.g. 90.130.70.73:25787
                            //Port according to answer = SecondToLastNumber * 256 + LastNumber
                            let s2 = try Socket.create() //Extra socket for data
                            try s2.connect(to: new.ip, port: new.port, timeout: 10000, familyOnly: false)

                            if s2.isConnected {
                                print("s2 connected")
                                try s2.write(from: "LIST\r\n")
                                answer = try s2.readString()
                                print("2nd socket: \(answer)")
                            } else {
                                print("s2 not connected")
                            }
                        } else {
                            print("Passive: Not 227!: \(answer!)")
                        }
                    } else {
                        print("PW: Not 230!: \(answer!)")
                    }
                } else {
                    print("User: Not 331!: \(answer!)")
                }
            } else {
                print("Connected: Not 220!: \(answer!)")
            }
        } else {
            print("not connected")
        }
    } catch let error {
        print("Error: \(error)\n\(error.localizedDescription)")
    }
}

"s2 connected" is printed but print("List: \(a5)") isn't, even long after the timeout period has passed. It doesn't seem to matter what I use for it, it's the same thing with 20000ms and it also happens with "NLST".

There's no error message, the app simply freezes and nothing happens.

Edit: After 15-20 minutes (timeout: 10000ms = 10s) I now got an error message:

Error: Error code: -9971(0x-26F3), Connection reset by peer The operation couldn’t be completed. (Socket.Socket.Error error 1.)

Closing the first socket before opening the second outputs the same error message instantly.

Kitura / BlueSocket

No reaction after timeout period has passed #175