The reason why it works when you shut it off and turn it back on is your clearing out your router's priority so when you shut it off and you reconnect your router is prioritizing your TV what will happen is let's just say you don't use the TV or it sits idle it then will designate more of your bandwidth to another item if you use qos you can manually dictate what you want your router to prioritize like tv. On the tv You click menu go to settings go down to the third option that states connection then go to network click on network go to open network settings now click Wireless and it will give you a list of all your networks like shown with the signal strength here you can see Netgear 10 5G is 5 GHz 71 is 2.1 GHz so you will not see the 5 GHz if it is 2.5 based off of the photo. Now best case scenario would be to have full bars if it's anything less than missing one bar try not use that Network. Note you also have the quick toggle menu at the bottom of your screen that will show you the signal strength. As far as you being connected to Wi-Fi in but not having internet connection. This happens when the TV is theoretically still able to barely contact the router however it cannot carry bandwidth through the air due to so much interference. Every time you add another device to your Wi-Fi your router divides the signal one more time so if you have 100 speed and you have 10 items connected in theory it will give each item 10mbps to use but if something else is connected and the router decides that it needs more bandwidth it could drop your TV down to one 1mbps . You will notice there is so many different types of routers on the market some of them are really inexpensive and some are them are very expensive there is Big reasons why this is routers are equally as important as a PC is in your home in this day and age the router needs to be able to not only consistently feed internet to something it has to do it through the air through walls and it has to decide what is priority and what is not and as our routers get older they get less and less value to us in your PC it's typically going to carry a much larger Wi-Fi card depending on what tier of TV you purchased from Samsung Samsung has a wide variety of Teirs $1,000 and down would be their budget then all the way up to their 8K line would be their highest consumer lines the higher you go the better the product is the better the Wi-Fi is the better the picture is the more features it has so on and so forth. I think of it like a PC you can get a PC that looks exactly the same on the outside but one could be a 500 and not so great and another one could be 2k an amazing PC. no one would be able to know unless they used it. As externally it just looks like a PC so there's always that to take into account. That's why it's so hard to just blank it and say all Samsung TVs have horrible Wi-Fi. But an easy fix to this is plugging it directly into an extender or moving your router centrally located closer to your TV turn on qos and prioritize your TV to the highest priority. Also just wanted to let you know I'm really just trying to help no argue I'm not sure how it comes across through text but wanted to put that out there😊
I recommended a great router because it's important if you want to have a better smarthome experience. I didn't say that was the only way to fix it. For me A 600 dollar router is worth every penny if it will make all your devices work better. As long as you have good service from your provider. Also to have a router under your tv is one of the worst locations possible. Don't take my word for it you can Google it but I did attach some quick Google searches for you. And I assume you can understand you would only need a hundred foot eternet cable if your TV was far away from your tv. As a way to hardwire it Via ethernet. And was just an example there is all different lengths Since you figured out how close it was I assume you would understand a short one would do. And would also fix your problem. But hey you think it's funny so keep enjoying a TV that doesn't connect more power to you😉 I was just trying to help. 
