Populating Tooltip Text from something like a VLOOKUP

Hi all, I'm very new to Power BI having first launched it today, but I feel I've come a long way :)  I've done a search here but can't really find what I'm looking for, so any assistance is greatly appreciated.

Some background - I have a program that monitors a large number (thousands) of devices and reports back those devices that fail to respond. Identifying them by location (name and coordinates), what they are and their address.  It spits out the information into three CSV files which in turn get sent to OneDrive for Business and have been added to a Power BI visualisation that looks like this:

Clicking on the segments of the pie chart automatically updates all the numbers and shows subsets of the full data in the table shown at bottom.  The map also updates to show the location of the outages.  The script runs every hour and Power BI refreshes it when its ready to, on its hourly schedule.

Here's the bit that I am missing.  When I hover over any of the addresses at the bottom, all that shows is the IP address of the device.  What I'd like it to show is a text field which indicates when that specific outage was first detected via the script.  One of the CSVs the script produces is a two column table with all of the IP addesses that failed to repond and the Date-Time it was first reported.  That CSV has been added to Power BI, but I can't work out how to use the data it contains to display the matching IP's date/time.

So what I need is when the table above generates, it needs to do like an Excel VLOOKUP to match the IP on the table with the corresponding IP in the other CSV and populate its Tooltip text with the contents of the adjoining cell.

Hope that all makes sense and is doable.  I'm super impressed with what I was able to achieve in such a short amount of time with PBI today.  Thanks in anticipation.