In the morning of December 15th, from 0900z to 1300z (4 AM EST to 8AM EST) the ARRL HQ network infrastructure will have a major upgrade performed.
While not specifically related to LoTW, it is likely that during this time period, you may not be able to reach the LoTW system (or any other ARRL system) until the upgrade is complete.
Please try to avoid this timeframe.
Thank you & 73!
Robert E. Naumann W5OV
Director of Operations