the dna40 uses Ni200 wire which is very low resistance, a typical coil is in the .10 range, were talking builds like .09, .14 etc... this Ni200 wire increases resistance as it heats up and the temp is controlled by measuring the resistance... for example a .1 build may wind up going up to say .16 at 400 degrees, this is how the dna40 controls temp, by measuring the resistance... if it sees an extra .02 lets say, this would severely impact the resulting control... once it detects abnormal resistance readings of any kind, even a few hundreths it ruins the control aspect, the dna40 will jump back to kanthal mode or just not reach any kind of vaping temps, etc... the dna doesn't deal with anything less than a rock solid stable resistance... many problems caused by 510 connections less than perfect, wire posts less than perfect, it's very intolerant to any kind of instability in the resistance reading...
I've tried many times to get a genny to work with temp control but it just at some point invariably shorts just enough to add a few points to the resistance and then bang, it just sucks. only successful build in a genny with the dna40 for me has been wrapping cotton around the tip of ss cable, q tip type thing, isolates the coil and works well but to me once you're using cotton in a genny it's no longer a genny, defeats the purpose in the first place... I tried over and over and over again with cable and mesh, really wanted to get this particular setup to work with temp control but it just ain't happening. no matter how much I get it to working fine it's only a matter of time till it just starts bugging out