testing USB tethering on my dual-sim Mi5s phone, it seems that I can not get it to work with the Swisscom SIM card here, whereas all works fine with the second SIM.
Connection to the internet on the phone itself, e.g. web browsing works fine.
Inserting the Swisscom SIM in my older Samsung Galaxy Alpha, the tethering works fine.
When comparing the APN settings on the two phones there are some tiny differences (proxy/port set/empty, authentification empty) , but I could not succeed to make it work. On the other hand: once the phone is able to access the internet, the APN should be ok, as far as I understand.
So currently I do not have an idea where to search and would be grateful for pointing me in the good direction.
I've recently bought a Swisscom SIM for my MI A2 dual SIM phone. When I switch data connection to that SIM I can access the internet via the mobile, but If I try to use the phone as an hotspot (tethering function) the connected devices cannot. Everything is working perfectly when using the other SIM (vodafone in roaming).
I've seen a similar post in April 2018 but no solution was there.