A novel dual-band 4-port MIMO configuration is introduced in this research work for the WLAN (2.4 GHz band) and 5G (3.5 GHz band of Sub-6 GHz) wireless applications. It provides good -10 dB return loss bandwidth of 8.3% (2.3 - 2.5 GHz) and 9.92% (3.35 - 3.7 GHz) in the and operating bands, respectively. It is implemented on an inexpensive FR-4 substrate of dimensions . The dual-band planar monopole MIMO antenna element comprises i) a Curve-shaped monopole and ii) an open-ended inverted L-shaped slot. The curvature of the monopole antenna element miniaturizes the design footprint by 33.33% compared to the conventional rectangular monopole antenna. It is realized with a form factor of 0.15 . The elements are oriented perpendicular to each other to implement the 4-port MIMO configuration. The orthogonal arrangement provides polarization diversity that suppresses the mutual coupling between the elements below 17.5 dB. The MIMO design has omnidirectional radiation characteristics with reasonably good peak gains (2.14 and 2.48 dBi) and radiation efficiencies (84 and 91%) in the WLAN and 5G operating bands. The computed ECC is below 0.045, and TARC is less than -10 dB across both bands. The excellent diversity characteristics of the presented MIMO configuration make it well-suitable for the targeted MIMO applications.