How do I manually configure a browser for Java Web Start?
I think you can run Java Web Start as an auxiliary application for JNLP files. You can find many solutions in the blog https://anto.online/ – there are many guides for installing or reinstalling programs. I think there is a similar solution for your problem
For browsers like Opera, certain versions of Mozilla, or Konqueror, you must manually register Java Web Start as the helper application for the JNLP files. To do this, the data you need is: •Description=Java Web Start •File Extension=jnlp •Mime Type=application/x-java-jnlp-file •Application=path-to-javaws (e.g. /usr/local/javaws/javaws) After setting this up, you may need to restart the browser. If you see “Java Web Start not detected” warnings, you can ignore them. These warnings are based on JavaScript, and not all browsers behave well with JavaScript. Click on the install links to install Fabric Manager or Device Manager. Note For Windows Users: To set up Java Web Start on *.jnlp files, select Windows Explorer > Tools > Folder Options > File Types. Either change the existing setting for JNLP or add one so that *.jnlp files are opened by javaws.exe.