HFSS Wave vs. Lumped ports at Ku band

I read a lot about it and found that for better accuracy Wave ports are the bread and butter of HFSS, however I still don't get the rules of thumbs of what are the right instructions to create it at any of different cases
For instance when I created Wave ports for 17.5GHz attached to microstrip according to the definition of wide as 5 times the microstrip width and high as 8 times the substrate height so the simulation warned me about additional modes that will create attention and thus I left with results that im not sure about them ... And also what is the right way to use Lumped ports what is the best way to define it for instance for same microstrip should I define the boundaries of the air box as radiation (near the ports) and other faces as finite conductivity? Or just leave it as air ... I looked at many examples but this not provides good enough explanations of why specific implementation was used in it's specific way

The modeling of microstrip lines in HFSS indeed has many alternatives. There might not be a silver-bullet solution. The usefulness of the simulation has to be checked with analytical calculation and/or measurement upon real samples.

My experience tells me both wave port and lumped port are applicable to the simulation of microstrip lines. However, wave port is more convenient, since it directly provides the characteristic impedance (given that port re-normalization is not enabled).