In this paper we report a detailed ESR spectroscopic study of the single-crystalline samples of the van der Waals compounds M2P2S6 (M2=Mn2, MnNi, Ni2), performed at an excitation frequency of 9.56 GHz, in a broad range of temperatures above the magnetic order, and at different orientations of the magnetic field with respect to the sample. Analyzing temperature and angular dependencies of the resonance field and of the linewidth of the Mn2P2S6 compound we have observed a significant change of the spin dynamics from the dominance of the 3D-like fluctuations close to the magnetic order to a relative increase of the 2D-like spin fluctuations at higher temperatures. Such a behavior, which is opposite to the development of the low-D signatures in the previously studied Cr2Ge2Te6 compound, can be explained by the difference in the type of magnetic order in Mn2P2S6 and Cr2Ge2Te6. On the other hand, MnNiP2S6 compound exhibits angular dependencies of the linewidth typical for the system with 3D-like spin correlations in the whole measurement temperature range, however the 2D-like correlations can be seen in the temperature dependencies of the resonance field and the linewidth. Ni2P2S6, in turn, does not show any 2D signatures. This suggests that varying the Ni content in (Mn1-xNix)2P2S6 one can control the exchange interaction, possibly also in the third dimension.