Weird Network Issues w/ Spotify

[exploitedthat]

I'm not sure what is going on but I can't seem to get Spotify to work on my home network on any mobile device. It works fine on my PC but not my tablet, phone, or chromecast. If I utilize my phones LTE connection everything is fine, even tried to create a hotspot and connect my tablet. It's one of those weird fringe cases I just can't figure out. Asked both my ISP and router manufacture, they both say the services can go through. Here is the list of how things work.

Nexus 5 (6.0.1) + Local WiFi = "Sorry, something went wrong."

Nexus 5 (6.0.1) + LTE = Works

Android Tablet (5.1.1) + Local WiFi = "Sorry, something went wrong."

Android Tablet (5.1.1) + LTE Tether = Works

Chromecast (1st Gen) + Local WiFi = "Sorry, something went wrong."

Chromecast (1st Gen) +  LTE Tether = Untested

Windows 7 PC + Local WiFi = Works

Windows 7 PC + LTE Tether = Works

Really love the service and want to go Premium but I just cant justify it if I have to burn my mobile data when utilizing it.

[user-removed]

First I would test Spotify with Public WiFi, I think by Local WiFi you mean your own modem's WiFi. If it's working with Public WiFi then there might be some IP-address confliction which you might fix through your modem's settings.

Open your modem's settings and look the devices in your modem's settings, if it shows your mobile phone there please remove it and save your modem's settings, then restart your modem and re-connect your phone to your Local WiFi.

[exploitedthat]

Yeah by local WiFi I mean the WiFi from my own router. I don't have a modem exactly. Local internet is provided by a Cat 5e cable with a switch upstream that I have no access to. I contacted the ISP and they swear that they don't block anything, inclined to believe them as spotify does work on my PC. For the record I only installed the application on my computer when I was having trouble with my phone/tablet, so it's not that they got bumped by the the PC, but I did clear UPnP just to be safe but it wasn't even listed. Also, checked my router and short of the DHCP list there really is no list I can remove the Android devices from.

I have tested my Android phone on a friend's WiFi and Spotify does work so it does seem to be a local network issue. Just no idea what.

[exploitedthat]

Always wondered why my tablet had trouble with amazon underground app. Tought it was some compatibity issue but with this Spotify thing I retested with a tethered LTE connection and it worked just fine. So whatever the problem is, it affects multiple applications.

[user-removed]

First I would do a Factory Reset for your router, if that doesn't help I think we need to do some IP-whitelisting, and that's not so easy task.

[exploitedthat]

Nothing. Also tried disabling the routers SPI firewall for the hell of it and nothing. 

You talking about whitelisting the following IPs on port 4070?

78.31.8.0/21
193.182.8.0/21
194.68.28.0/22

Edit: Tried putting my tablet in a DMZ and still nothing. This is beyond fustrating and I have a funny feeling its the ISP.

[user-removed]

Did you contact your ISP? Has there been any improvements?