I would really appreciate some advice, at home I have Pilsner keg beer in my cellar at 12c (53f)it is being propelled with a gas cylinder containing 80%nitrogen and 20% carbon dioxide which is at 2.6 bar. The beer tap unit is a Pygmy brand has an integrated cooler which through a coil cools the beer to around 6c, and a pilsner type tap for creating proper Pilsner type beers. I am concerned about the way this is set up beer seems slightly under carbonated, head doesn’t last so long. Thank you all for any advice!
You'll have to take what I say with a grain of salt, I am not very experienced in working with that high of a nitro mix, or serving at that temp.
I'm surprised you're able to serve beer at 2.6 bar, that would be like a firehose out of one of my taps. Even for a nitro mix, I would think you'd still be under 2 bar. However, lighter carbonation is going to be a result of a nitro mix that high, especially after sitting for a while.
I'd lower the keg temp if you can stand to, simply because that's already quite high PSI for serving and going above 2.6 seems nuts unless your tap lines are fifty feet long.
You may be able to get some advice from the brewery or distributor that is more helpful. Other than that, I'd get a higher CO2 mix if you're typically drinking lagers. I find the nitro mouthfeel on lagers and light ales to be a little weird (creamy pale ale..no thanks!)