Add source hxxp://fusion.tvaddons.ag and install the Idigo plugin. From PROGRAMS click Indigo>Search by: Adon/Author and search for Easy Advanced Settings and install. Open PROGRAMS>Easy Advanced Settings>Edit Settings>Network Settings>Network and click the catagoryiesyou want to edit. Then backspace to Audio/video playback settings>PVR and make your changes backspace Write xml file. Below are the settings that I use. You can copy and paste to a text file and save as advancedsettings.txt then change the .txt to .xml and move to your Kodi userdata folder or use the values below and the addon to tweak the values to fit your setup. Increasing the cachemembuffersize WILL NOT decrease buffering if you go to high you will use all RAM and make Kodi crash. The other values you can play with. Check YouTube, The Kodi Wiki. and search Google for more info.
<?xml version="1.0"?>
<!-- Created using Easy Advanced Settings addon -->
-<advancedsettings>
-<network>
<buffermode>2</buffermode>
<cachemembuffersize>50000000</cachemembuffersize>
<curlclienttimeout>10</curlclienttimeout>
<curllowspeedtime>10</curllowspeedtime>
<readbufferfactor>6</readbufferfactor>
</network>
-<pvr>
<maxvideocachelevel>85</maxvideocachelevel>
<minvideocachelevel>65</minvideocachelevel>
<minaudiocachelevel>65</minaudiocachelevel>
</pvr>
</advancedsettings>
<?xml version="1.0"?>
<!-- Created using Easy Advanced Settings addon -->
-<advancedsettings>
-<network>
<buffermode>2</buffermode>
<cachemembuffersize>50000000</cachemembuffersize>
<curlclienttimeout>10</curlclienttimeout>
<curllowspeedtime>10</curllowspeedtime>
<readbufferfactor>6</readbufferfactor>
</network>
-<pvr>
<maxvideocachelevel>85</maxvideocachelevel>
<minvideocachelevel>65</minvideocachelevel>
<minaudiocachelevel>65</minaudiocachelevel>
</pvr>
</advancedsettings>