This consistent issue with Samsung products. I'm in the same room as the router with my S21 Ultra and I have tab S8 Plus, yet my tablet says it doesn't connect. I just had this  with my tab S6 and my note 8.

How is this still an issue through multiple variations of Samsung products that I own I've had iPhones never had the issue. I'm in same house router is in in place. doesn't mean I'll switchback to the iPhone but it's been a long time and still no fix. 

I know some may say it's a modem or router but it's not. I have changed it more than once. Now I have an Asus router that has no issues covering the house from one