UE initially latch with 5G network but goes to 4G coverage

5G NR
,
1

Hi All.
My UE initially latch with 5G network, after 40 sec it goes to 4G coverage.
Then gradually 4G coverage reduced to no coverage.

Any help?
Any similar things happened in your observation?

2

What do logs say?
Registration Reject, No available slices, can be any reason…