I came across this topic whilst trying to figure out the text width for UTF-16 strings - the solution we used was to write the text/font to the caption of a string control with 'size to text' enabled and then read the Caption.Area Width property:
I think the only issue is that LabVIEW adds a few pixels of spacing around the caption - but I think this will be a constant that can be removed.
I take it you don't have a dedicated connection between the two devices. Things that can break the system that come to mind is the routing and if there are duplicate IP addresses on the network.