I use a dual-SIM on my Asus Zenfone Max Pro (M1) running on Android 9 to have data from an Italian and a German operator at the same time.
It works fine on the phone, but I noticed that when I use it as a WiFi hotspot (to connect my laptop), most of the times I got messages like “connected, no internet”.
My workaround solution is to disable one of the 2 SIM (toggling the SIM-selector in the Android settings), disconnect the laptop, and reconnect. It works, but it is very frustrating.
I suppose there is a better way to set my network properties on phone and laptop, such that they can communicate better.