SFO - WUH (Wuhan) - CAN (Guangzhou) - DEL with flight # CZ660 - Transit Visa

I am US Citizen traveling from SFO - WUH (Wuhan) - CAN (Guangzhou) - DEL with flight # CZ660. Layover is about 9 hr 5 minutes. I am transiting two cities in PRC. As I understand this flight require me to get down in WUH and then board again in same flight to CAN. Do I need to apply for transit visa in advance?
Reading blogs indicates that if it is less than 24 hours stay, there is no need to get advance transit visa however when I called China Southern Airlines US office I was told that I should get one since there are 2 cities involved.
Any clarification/guidance/experience will be helpful? Thank you.