Here is the spew I get, this is running 3.4.5 on the duet. The failure shows up on each attempt,
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Attempting connection at 192.168.1.69:3000...
Connection refused. Make sure the device is turned on and the connection details are correct.
Attempting connection at 192.168.1.69:3000...
Connection refused. Make sure the device is turned on and the connection details are correct.
Attempting connection at 192.168.1.69:3000...
SENT: GET
http://192.168.1.69/command GETPRINTERSTATUS
SENT: GET
http://192.168.1.69/command GETPRINTERSTATUS
SENT: GET
http://192.168.1.69/api/v1/system
READ: <!DOCTYPE html><html lang="en" translate="no"><head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=0"><meta name="google" content="notranslate"><!--[if IE]><link rel="icon" href="/favicon.ico"><![endif]--><title>Duet Web Control</title><link href="/css/app.23e90265.css" rel="preload" as="style"><link href="/js/app.d0ad7b20.js" rel="preload" as="script"><link href="/css/app.23e90265.css" rel="stylesheet"><link rel="icon" type="image/png" sizes="32x32" href="/img/icons/favicon-32x32.png"><link rel="icon" type="image/png" sizes="16x16" href="/img/icons/favicon-16x16.png"><link rel="manifest" href="/manifest.json"><meta name="theme-color" content="#2196f3"><meta name="apple-mobile-web-app-capable" content="yes"><meta name="apple-mobile-web-app-status-bar-style" content="black"><meta name="apple-mobile-web-app-title" content="Duet Web Control"><link rel="apple-touch-icon" href="/img/icons/apple-touch-icon-152x152.png"><link rel="mask-icon" href="/img/icons/safari-pinned-tab.svg" color="#2196f3"><meta name="msapplication-TileImage" content="/img/icons/msapplication-icon-144x144.png"><meta name="msapplication-TileColor" content="#000000"></head><body><noscript><strong>We're sorry but Duet Web Control does not work properly without JavaScript enabled. Please enable it to continue.</strong></noscript><div id="app"></div><script src="/js/app.d0ad7b20.js"></script></body></html>
SENT: GET
http://192.168.1.69/api/v1/system
READ: <!DOCTYPE html><html lang="en" translate="no"><head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=0"><meta name="google" content="notranslate"><!--[if IE]><link rel="icon" href="/favicon.ico"><![endif]--><title>Duet Web Control</title><link href="/css/app.23e90265.css" rel="preload" as="style"><link href="/js/app.d0ad7b20.js" rel="preload" as="script"><link href="/css/app.23e90265.css" rel="stylesheet"><link rel="icon" type="image/png" sizes="32x32" href="/img/icons/favicon-32x32.png"><link rel="icon" type="image/png" sizes="16x16" href="/img/icons/favicon-16x16.png"><link rel="manifest" href="/manifest.json"><meta name="theme-color" content="#2196f3"><meta name="apple-mobile-web-app-capable" content="yes"><meta name="apple-mobile-web-app-status-bar-style" content="black"><meta name="apple-mobile-web-app-title" content="Duet Web Control"><link rel="apple-touch-icon" href="/img/icons/apple-touch-icon-152x152.png"><link rel="mask-icon" href="/img/icons/safari-pinned-tab.svg" color="#2196f3"><meta name="msapplication-TileImage" content="/img/icons/msapplication-icon-144x144.png"><meta name="msapplication-TileColor" content="#000000"></head><body><noscript><strong>We're sorry but Duet Web Control does not work properly without JavaScript enabled. Please enable it to continue.</strong></noscript><div id="app"></div><script src="/js/app.d0ad7b20.js"></script></body></html>
SENT: GET
http://192.168.1.69/api/v1/system
READ: <!DOCTYPE html><html lang="en" translate="no"><head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=0"><meta name="google" content="notranslate"><!--[if IE]><link rel="icon" href="/favicon.ico"><![endif]--><title>Duet Web Control</title><link href="/css/app.23e90265.css" rel="preload" as="style"><link href="/js/app.d0ad7b20.js" rel="preload" as="script"><link href="/css/app.23e90265.css" rel="stylesheet"><link rel="icon" type="image/png" sizes="32x32" href="/img/icons/favicon-32x32.png"><link rel="icon" type="image/png" sizes="16x16" href="/img/icons/favicon-16x16.png"><link rel="manifest" href="/manifest.json"><meta name="theme-color" content="#2196f3"><meta name="apple-mobile-web-app-capable" content="yes"><meta name="apple-mobile-web-app-status-bar-style" content="black"><meta name="apple-mobile-web-app-title" content="Duet Web Control"><link rel="apple-touch-icon" href="/img/icons/apple-touch-icon-152x152.png"><link rel="mask-icon" href="/img/icons/safari-pinned-tab.svg" color="#2196f3"><meta name="msapplication-TileImage" content="/img/icons/msapplication-icon-144x144.png"><meta name="msapplication-TileColor" content="#000000"></head><body><noscript><strong>We're sorry but Duet Web Control does not work properly without JavaScript enabled. Please enable it to continue.</strong></noscript><div id="app"></div><script src="/js/app.d0ad7b20.js"></script></body></html>
Connection failed.