Good day Mainzer1954
WLAN client and hotspot are 2 different services
For more details about hotspot, please look into the following link
https://wiki.teltonika-networks.com/view/RUTX11_Hotspot
You are connecting to public WLANs to try to get internet breakout
Make sure that you are enabling masquerade in the firewall rules and that the WLAN client you are making is with a higher priority than the mobile interface for example
As you don't know how the other LANs or WLANs are configured
They could be limited access or only allow access via a guest portal
Which could limit you to 100Mb of data for example
If the setup you have done works in other areas, then it could be a limiting factor from the public WiFi you are connecting to