Thank you for the detailed post! I took a quick look at this and find it very odd it’s only adding the slash for /js and not the others. Furthermore, I took a look at my code and the /js is only defined on one line:
https://github.com/OpenSprinkler/OpenSprinkler-App/blob/master/www/js/main.js#L1026 and I can’t imagine how a slash could be added so my theory is the reverse proxy is adding the slash. If the packets you are showing me are down stream of the proxy, then could you provide the proxy configuration or at least double check to ensure it’s not adding the extra slash?
Also when using the web browser UI, the slash is not present correct?