@Ray: Thanks for the immediate response!
In replying to your question, I imported previous configurations. However, in order to overcome the issues, I have tried all ‘Reset’ options, i.e., ‘Clear Log Data’, ‘Reset All Options’, ‘Reset All Station Data’; after the last options, I have imported previous configuration.
Regarding the Ethernet case (hoping that this information would help in resolving the issue), I am using the TL-MR200 4G Router.