If your S1 limitation is just 1 Gbpsec and you have 6 cells of 4G and 3cells of 5G at some point new connections will nto be accepted due to TNL limitation.
Huawei has counter for this.
Baseband is board limitations, max numbers of RRc users is license limitation not hardware limitation.
For Huawei, suggestion is to open huawei counter list, go to RRC reject group counters.
There are list of reject cause, that mean resource involved in admission control.
TNL mean eRAB setup failure when MME give eNB one IP address of user-plane CN to setup transport path for data. But eNB fail to setup, ping to sgw IP address.
Baseband hardware also limit RRC user - some board support 3.600 users, some other support 7.200 or 14.400 user.
User number often limited by license because operator purchase license much less than hardware capacity.