A work around that works on my android 9 tablet is as follows.

From the google play , download the app to link tethering on a working device like a phone.

If the phone is running android 10 ( this is fine ) .

From the tp link tethering app on your phone.

Use the share your internet connection .

Choose to share your connection.

Because anyone can connect to your device .

Choose encryption.

Popup window will open with password .

Put in your password for your router.

My problem was , the phones in the house connected to the router , even chromecast .

But not my tablet.

This was all a wifi connected but no internet on my tablet.

This fixed things for me.

I finally understood it was an android 9 on my tablet , which I put in , is data only sim card from my mobile modem.

It seems the phone android 10 is communication with my sim card , fine .

But not android 9 .