Find previous and next date

Hi svendaems ,

Thanks for your concern about this case!
svendaems Have you solved your problem? If not, please try this way:
Because today is not May 3rd, so I use May 3rd to test:

Previous Patching = 
VAR PatchingName = tblPatching[Name]
VAR RelatedWave = RELATED(tblServers[Wave])
VAR TargetDate = CALCULATE(
    MINX(
        FILTER(
            tblWaves,
            tblWaves[Wave] = RelatedWave &&
            tblWaves[Date] <= DATE(2024, 5, 3)
        ),
        tblWaves[Date]
    ),
    ALL(tblWaves)
)
RETURN TargetDate

Next Patching = 
VAR PatchingName = tblPatching[Name]
VAR RelatedWave = RELATED(tblServers[Wave])
VAR TargetDate = CALCULATE(
    MINX(
        FILTER(
            tblWaves,
            tblWaves[Wave] = RelatedWave &&
            tblWaves[Date] >= DATE(2024, 5, 3)
        ),
        tblWaves[Date]
    ),
    ALL(tblWaves)
)
RETURN TargetDate

Please change the 

DATE(2024, 5, 3)

into

TODAY()

Best Regards,
Dino Tao
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.