Turn off the “Mobile Stats” button from the toolbar (last button on the right) if you are making a PC version material. Those warnings are only applicable to Mobile rendering (ES2).
One thing to note in case you aren’t already aware and are using version 4.6 or greater is that you now have access to 128 samplers through “Shared Samplers”. Right now it looks like you have 3 more textures before hitting the limit 16 separate samplers, but you can get more by clicking on a texture sample node and changing the “Sampler Source” to Shared Wrap (or clamp if you set that property on the texture itself, but usually it is wrap). The engine creates a kind of texture atlas automatically in the background allowing you up to 128 textures.
But is only for 4.6 +, versions before are limited to 16. So if you still need a lot of textures, that will be the best way to go.
Thanks for the information. So if I have a texture sampler duplicated 3 times I have to set each one to Shared Wrap or only one of them would do the job?
I am pretty sure you will need to set them all to Shared Wrap as one or two samplers without that value set may appear to UE4 as a separate texture sample. So long as all three are set the same it should be fine, UE4 will only actually use one of the three samplers in the total count since they are identical.
I could be wrong on as I have never actually seen it mentioned before… So I’m not sure it technically is required but that is how I would (and do) set them up.