Definitely not. I’ve written about this in the past - every now and again I dig out this post, suggest you have a read to get a bit of a grasp on what’s going on and why:
To fix this, you need one of the following:
- a subdomain (sorry, I know you’ve said this isn’t possible for you on free DynDNS service), OR;
- the app in question to support a base URL setting, OR;
- to start filtering all the HTML and headers that come back from the app, to manually replace incorrect references with the correct, subfolder-prepended URLs
HTML filtering was possible in v1 as a third-party plugin, I don’t think v2 has this yet (although it should be pretty straightforward to implement, I think!). Even so, that approach was complex and fraught with potential footguns, as you have to be very precise with your rules to get the results your browser will need.