Sounds like they have had a lot of issues today with connection. They mentioned something about missing information, they had me turn it off while they sent the data to my phone. Once it powered back on it was working just fine with 4g lte even on wifi.
I have a similar issue on my S10 5G on T-mobile. I cannot get LTE speeds or connection when set on 5G/LTE/3G/2G automatic model It iwll not default to anything but 2G and has no data. I have to manually switch the phone to the LTE/3G/2G mode for it to get high speed data. Both T-mobile and Samsung do not have a fix. T-mobile told me to return the phone for a refund if I am not happy. She seemed to admit it is a Samsung problem that needs a software or firmwae update that might not come for months. Very sad to see on such an expensive phone
I've noticed a few network issues with the s10 5g. First issue is that it switches to 1x when connected to wifi, which is not a big deal unless you disconnect from wifi, then it takes a little bit to find 3g-4g. Next issue, is that it has a hard time finding 4g LTE. My wife's phone will state 4g LTE, but mine will be at 3g. Also, have noticed it switch when on a call to 1x. Anyone else having these issues, kind of frustrating.