I just received a new SIM card that I want to use in an iPhone 4S. The phone reports decent 3G connectivity and can make phone calls, but does not connect to data services. Data services work with older SIM cards from the same operator. In addition, the new SIM card works when it is installed in newer phones (testet on an iPhone SE and an iPhone X).
Thus, out of six possible combinations of phone and SIM card, the only one that does not work is the oldest phone with the most recent SIM card. All SIM cards come from the same carrier and the mobile data network settings are the ones recommended by the operator and identical on all phones, except for the older phone that is a 3G phone, while that the new models support 4G / LTE.
Can the new SIM card be incompatible with older phones? If not, what can be the problem? Carrier support has not been useful so far.