I think I can clarify my post but whether it helps or not depends on your current (& future) hardware. Here is how I would simplify my findings:
1). The optical output on my Samsung TV (& probably most, if not all), is limited. It main purpose is to drive a sound bar. It does not have much flexibility in format choices and it lacks in SQ. I know for sure that it won’t output digital data at higher than 48 kHz, and I do NOT believe that it is really outputting 24b wide data uncompressed data because of its poor SQ.
2. If you have a Samsung Blu Ray player with WiFi (like the UDP-M9500), since it has much more powerful dedicated audio processing capability, I find that streaming from the Blu Ray player allows an extremely wide choice of output formats on its optical port. 24b/96 kHz uncompressed PCM or uncompressed Bitstream data in many multi-channel channel configurations (like Dolby) is always available and sounds great.
3. In order to exploit the player’s better audio processing capabilities you need to source the stream directly from the Blu Ray player. It comes loaded with fewer APPs than the TV, but you can load up more.
4. If you are sourcing media directly from the TV (like with a SAT source), I don’t know of a way to get the Blu Ray player to handle that processing.
5. Instead, you will have to use the HDMI 2.0 audio out port on the TV and send that to a device that accepts digital data directly like an A/V receiver or a Digital-to-Analog Converter that ahas an HDMI input. The TV has a more powerful set of codecs to handle decoding the digital content for its HDMI outputs. There may be one (possibly 2) HDMI ports that is labeled HDMI 2.0 or HDMI 2.0a or HDMI-arc. That port will OUTPUT clean digital audio off the TV and down into whatever is processing that for your audio system.
6. In US 2019 models, the HDMI 2.0a ports are NOT duplex capable until you get up in the 75 inch range. For a smaller TV, you only get audio out, not in, on that port. To get full duplex (bidirectional paths), the ARC (Automatic Return Channel) enabled port on the HDMI 2.x port must be implemented, something that cost precludes for all but 75” and up models.
So, in summary, if you don’t have a WiFi 4K Blu Ray player, and you don’t have an HDMI 2 capable A/V Receiver, you will be stuck with the limitations of the TV’s optical port.
If you get or have a WiFi enabled Blu Ray player (hopefully 4K), then any thing which can be sourced directly from the player will then give you a much better SQ output on its optical port and have a much wider set of format choices on your menu.
For the SAT TV mode, AFAIK, the Blue Ray player cannot be inserted in that loop. You can still bypass the optical port if you get or have an HDMI 2+ A/V Receiver or equivalent. HDMI 1.0 won’t handshake with the 2.0 port from the TV.
There are two points here that make me ponder.
A). Your problem as stated is dropouts and not stated as continuously poor SQ.
B). HDMI 2.0, 2.0(a) and, especially HDMI 2.1 are fully capable but rigidly enforce the HDCP copyright protection safeguards.
Problem A may be as simple as replacing your S/PDIF optical cable. Or, it may be much more troublesome if it is in anyway being affected by the HDCP (High-Definition Digital Copyright Protection) data police.
Media ownership and theft thereof is where the biggest legal fees go.
The manufacturers have responded to that threat by implementing HDCP and extended it thru the progression from HDMI 1.x thru HDMI 2.1.
What this does is create a Nanny State of paranoid control inside of the TVs.
For example, if you feed your TV with both HDMI 2 and HDMI 1 inputs (even HDMI 3 from game boxes), the nanny will sooner or later notice that you are possibly trying to hijack 4K quality because you have HDMI 1 ports activated.
Those ports may be attached to equipment that lack the HDCP handshaking expected, so it will say, “Whoa. Hold on there Sir. I am going to downgrade my video to 1080P and do harm to the audio output as well because your ‘older’ equipment may be making illegal dupes!
Nanny will rule the roost, att least until you run out and buy all HDCP/HDMI 2.1 compliant equipment in your stack.
The manufacturers have turned the liability of being sued for copyright violation and the cost of implementing the much higher BW ‘new’ fully compliant HDMI standards into a feeding frenzy bonanza where all of their (& others) HDMI 1 equipment is suddenly rendered obsolete, forcing you to buy not just the 4K TV, but to upgrade every component.
It puts a new meaning on ‘Fire Sale.’ You might as well have a fire destroy every device that connects to your new 4K (or 8K) TV so you at least get some insurance recompense.
As far as the MFGRs are concerned, its a Bright New Day! They figure we are all Nits, and we we sheep-walk to the order bar and re-buy EVERYTHING. They give us more nits of brightness while viewing us as dim-nits.
If you replace the IR optical cable, and still get dropouts, there is one last cheap fix that may slightly be possible. The total GPU/codec horsepower is limited, and if you have all of the extra modes under Picture/Expert Settings turned on, turn them all off and see if that makes any difference.
If after swapping in a new optical cable and disarming process demanding expert picture processing settings, you still get audio dropouts, I think you will have to expend more money.