After Post No. 4 above, I went to the next page on this forum and found reference to a real name registration policy in China. China Unicom stated:

"To comply with the “real name registration policy” imposed by the competent authority of Mainland China, all telecom operators in China who provide Mainland China mobile numbers are required to collect the personal data from their customers in order to comply with the real name registration policy. Since the Mainland China mobile number of CUHK’s “1C2N” (including the Mainland China mobile number of prepaid and postpaid services) are provided by the telecom operators in China, we have to comply with the policy.


Therefore, all CUHK’s 1C2N prepaid card users and new 1C2N postpaid (monthly fee plan) subscribers after December 15, 2016 would be required to comply with real name registration policy in order to activate or continue to use the Mainland China mobile number associated with 1C2N service. The use of Mainland China mobile number by postpaid customers during current contract period will not be affected. Furthermore, real name registration policy will not affect the use of Hong Kong mobile numbers provided by 1C2N services. You may refer to Office of the Communications Authority (OFCA)" See https://www.cuniq.com/hk/realname.html?country=hk_en

Is it possible that this policy or something similar caused the problems that we had in Nanchang?