@Raed 

Cause all devices work well except the samsung tab A6, the router should be working fine, while we can do some troubleshooting first; 

Please click here to check the IP and gateway of the tablet when it stops working. 

And please try to forget the profile and reconnect to the TP-Link wifi to give it a go.

Besides, you can assign a static IP for the samsung tab to give it a go. 

Good day. 

@Raed 

Please click here to get the instruction to remove the profile and reconnect to the TP-Link wifi. 

Note: Here we take Windows 10 as example.

To assign a static IP for the tablet, you can refer to the instruction below.

https://www.tp-link.com/support/faq/41/ 

Besides, please ensure that the firmware of TL-WR941HP is up to date.

Per  I said before, you can give samsung a call to get some help cause they are more professional about their product.

Good day. 

@Raed 

I do believe what you said that the tablet works well with other routers, while per you said, all other devices work well with the TL-WR941HP except the tablet, and it is just a troubleshooting method. They are more professional about their product, I think they can give you some helpful suggestion as well.

Besides, there are some other suggestion mentioned on my last reply, you can give it a go.

Good day.