TV Plus channels are unavailable

[Dbu7204]

I have a Samsung UE40MU6400 TV purchased in June 2018. It worked perfectly until a few weeks ago when, after an update to the software arrived, the Samsung TV Plus app doesn't work any more.

Although the app starts and seems to be working OK, when I choose a channel I get the message "This Samsung TV Plus Channel is currently unavailable" as shown in the photo below.

Other streaming apps such as BBC iPlayer or Netflix work perfectly OK and settings shows the Network Status is OK. The "software version" is "T-KTMDEUC-1400.3".

I've also tried:
- Leaving the TV on TV Plus for an hour to see if the channels would become available - they didn't
- Doing a reset of the TV. It made no difference.

I am also wondering if this is a firewall issue as my router might be blocking some ports that the TV Plus needs.

Any suggestions on what the problem might be and how to fix it?

[CU7000TvOwner]

There are some reliable utility tests by Steve Gibson see link below,

that can be run from a PC on your same network to see if there are closed ports that should be open. I will never to an update again with out first reading the reviews on it first. I wish I could revert 1310.3 back to 1310.1 which was what it arrived with in the box. !! S+ is ok on mine but it is random glitches that erase my favorites, or restore deleted S+ channels. OTA channels are not affected. There are many useful S+ channels about 300 total. I find about 100 of them are of interest to me. They are organized into interest groups which helps when I re do them.

https://www.grc.com/su/portstatusinfo.htm

https://www.grc.com/lt/leaktest.htm