Galaxy A5/Marshmallow Update WIFI connectivity - I've tried every resource available and none of them have worked.

I'm have very strange Wi-Fi connectivity since updating to Marshmellow 6.0.1 recently on my Samsung Galaxy A5.

Let's just first state - up until this point, my phone worked 100% normally with perfect functionality. Following the update, my home wifi immediately began issues. Connectivity was set, but certain apps would not work. Snapchat would not load or send, and I could not open the play store. After some fiddling and a manual download, I was able to fix the Play Store, however since then, multiple apps have lost functionality.

It's more bizarre than that though. For instance, Snapchat works on every other wifi and 3g. It can also send and recieve text, but cannot send/recieve photos (personal or story).
Messenger will load text, but cannot send or recieve photos.
Facebook sometimes loads, sometimes doesn't.
Instagram works 90% of the time, but sometimes will not.
Tinder works fine.
Other apps seem to all be ok, such as email, calander.

This however is frustrating because these are the apps that use the most data and which I need my home wifi to work most on!

I've tried EVERY single fix on the internet:
Toggling Airplane Mode
Continual Restarts
Continual Reboots
Deleting and Reinstalling Apps
Clearing Cache Partition of Old Software
Cleaning Cache of Apps
Removing Sim
Insertion of Memory Card
Forgetting Wifi Network
Changing DNS on phone
Changing DNS on home wifi network**

I cannot fiddle much with my home network as I live with my family and my internet is routed as part of our own IT network (my uncle is an IT guy, and No he will not know how to fix it with the phone). Therefore when I changed the home network it screwed things up.

Is there anything else I can do? I have been told by the staff at Samsung a factory reset will not achieve anything as it seems the problem is my home network. Why should I have to alter a home network (in ways that I have no idea how to anyway) to fix a problem that did not exist before?

Is there absolutley anything anyone can suggest doing?

Thanks

Jack