Trouble connecting from Android device

[Uncle Stan]

Recently, I began having trouble logging into my Subsonic server from my Android device.

The port is open, I can get in just fine from my browser, and I can hit the Demo server and another server with no problem. However, when I try to connect using my phone and the Subsonic app I get four tries attempting to resolve a "network error" and it tells me to check my information. It is all correct. I have tried rebooting my cable modem and router, re-installing the app, and creating a new user.

I am at a total loss for an explanation.

Geeky stuff that may help:
Windows 10 Pro, Version 1511, Build 10586.420
Subsonic 6.0
Moto X, Android 5.1 Build LPAS23-39.7-1
Netgear WNDR3700v5, port 4040 opened automatically

[alphawave7]

Open the browser on your Moto, and navigate to your public IP address and port 4040..does your server pop up? Who is your provider?

[Uncle Stan]

It's interesting that the phone connects using both the app and the browser as long as I am NOT connected to my network! I connect with no problem when on 4G, but get a collection of error responses when I turn on wi-fi. Connection from an outside network seems to be no problem. One of those things that make you go "Hmm."

My ISP is Optimum (Cablevision). I thought they might be port blocking (they've been known to do that) but the fact that I can get in from external networks seems to negate that argument.

[alphawave7]

Sounds like the router loopback issue...no explanation why it worked and now it doesn't, unless the ISP updated your router firmware without your knowledge. I use my local IP:port as 'Home' server, and my subsonic.org addy as 'Away' server and this has served me well for years, even though my router does work fine.

[Uncle Stan]

OK, thanks for the perspective. Guess I'll just keep poking at it until something works.