This article proposes a comprehensive guide to simplify the design procedure a multi-layer double passband metasurface filter. An inverse design model is used to estimate the geometrical dimensions, and the filter is studied in 6G frequency bands. Generalized sheet transition boundary conditions (GSTCs) are used to explain the effects of various parameters on the frequency response and to determine resonance type in the reflection spectrum. The equivalent circuit method is explored to understand the filter functionality, and vanadium dioxide (VO2) is incorporated to adjust filter characteristics, enhance the bandwidth, and coverage of a new band in 6G.