LG UltraFine 5K Display can become unusable when near a router

I got my monitor today and it doesn't work. LG technical support confirmed the following:

1. Monitor does not work near a router.

2. MacBook must be to the left or in front of the monitor.

3. Thunderbolt cable shipped with monitor might be defective.

LG is shipping me a new cable to try, but I only have 14 calendar days to initiate a return.

There was a Thunderbolt 3 problem last year with Dell's TB15 docking station that resulted in a recall. I believe the postmortem on that was the wireless card in the laptop causing interference on the TB3 IC.

I wonder if this is a similar issue?