OMFG I finally fixed this infuriating problem!!! First off, I tried all the other solutions; soft rest, hard reset, I even switched between WiFi and Ethernet conntiins, still no fix. It wasn't until I read a post somewhere on here and I saw a mention to DNS and I looked at what mine was and discovered it was manually entered and not automatic. This was not a surprise because I remember changing it to a specific one (long story short, I setup a raspberry pi that worked as a DNS to block all ads on every device that's in my house haha). Well, I just changed the DNS back to my router's old address I was using before my little project and after another SOFT reset, the tv turned back on and immediately signe don t my Samsung account and I knew right away it was gonna work again. Anyway, that was my fix. I'm not sure my particular solution will work for others (it was pretty specific to my situation) but maybe someone has their DNS address setup that doesn't jive with Samsung. Try changing it and maybe that'll help too. Just remember to soft reset after the change. Good luck!!!
Excellent find! Yes, it turns out that samsung smart TVs are using a few different domains that are on the standard pi-hole (raspberry pi) DNS installations. Grrrr. And its not just samsung.com. I am not sure if the findings below are static or not. But, for sure right now many of the web endpoints that the Samsung Smart TV refers to at login time are being blocked.
Here is how to find the endpoints that are being blocked by your pi-hole: login to your pi-hole console, and open the Query Log. On your Samsung, try and do a Search, enter two or three characters, and get the Unable to Connect to Server message. Refresh the Query Log. See the Red entries
in the Query Log for some names with samsung in them, longer names? Whitelist them.
Go through a few pages to make sure you got them all.
Now, turn off the samsung TV, wait 5 or 7 seconds, turn it back on.
Now try and search. If it still fails, repeat the above process to find the samsung
host that needs to be whitelisted.
After tuning using the one host below, I have a pi-hole that continues to protect the house (about 20% of queries are blocked), but I can still login on the Samsung Smart TV, and search, install apps, etc.
Here are the results of my digging into this connection problem:
At "login" or "search" time, the Samsung Smart TV Software (version 1361) communicates with a handful of exterior website endpoints, and for right now (2020 Sep 20) many of those web endpoints appear to be on standard Advertising block lists.
These are a few of them., they all have samsung in the name, and all were being blocked by the pi-hole DNS. At first, whitelisting one of them helped, but two days later, I had to whitelist the others. So far, I have been able to keep the samsung advertisements off the home row by not whitelisting the the samsungads hosts.
Not sure why so many Samsung endpoints are on the standard pi-hole block lists, but my guess is there is a good reason.
In any case, tune your Rasberry PI Whitelist and your Samsung Smart TV will behave a bit better.
This adjustment to our rasberry pi DNS (aka pi-hole) also fixed many other apps on the Samsung Smart TV that had never been working : Met Opera, Hulu, Tubi. All of them were failing due to the samsung sites being blocked.
But, definitely solved.