Interesting. To my knowledge, anything higher than the bandwidth of Dolby Digital is too much to send through an optical cable, and I’ve never seen eARC, or even ARC carried across optical, due to the one way nature of it. Optical, assuming it doesn’t contain ARC or eARC also can’t do the sync with video inherent in the two ARC specs. 

Can you provide a link to this cable you’re using?

Let me first say, that I am relieved that I totally did not imagine 1. It working perfectly, 2. That I ordered the cable based solely on the non present requirement of E-arc lol.  

https://a.co/d/8F604ah

 
to be clear, I had not been aware of such general limitations and thus was not skeptical in the least. But also, it’s not too cheap, and nearly completely sold out. 
 

https://share.icloud.com/photos/085tNDDVpFdSIE6HEk5D1JYaQ

Interesting cable, it converts HDMI 2.1 into an optical signal at the TV and then back to HDMI at the speaker. I didn’t realize anyone was doing that.

Projector folks might get a reliable connection on the 33 foot one saving them the current conversion problems when going long distances.

Ultra High Speed 48Gbps】The HDMI to HDMI cable supports 48Gbps data transmission, and the video will no longer stutter or lose frames. Create high-definition and stable 3D stereo image transmission. The latest high bitrate audio formats, including DTS Master/DTS:X/Atoms/HDCP2.3 and Enhanced Audio Return Channel (eARC)).

It’s interesting, but a one way cable, and I’m surprised it makes any difference, since it is adding two conversions to the data stream, but thank you for the link. 

Fortunately, I don’t have any issue on my Samsung or LG TV’s eARC connections, using the Sonos supplied cables to my Arcs. 

The one-way isn’t going to do the “Sonos to TV” CEC signalling, not sure how much impact that will have.

Read a bunch of the reviews and it wasn’t mentioned there or in the detailed specs.

A wire HDMI cable is inherently two way. This cable is making a digital to digital data transformation at each end. For the most part there is no need for the cable to be two way. Source video goes to the display and audio return goes back to the source. CEC data is two way at a very low bit rate.

There is no specific mention of CEC transmission for this cable.

I would like to just be very clear here that I use a Samsung frame and I previously did not have any problems with the cable that came in the box however I theory crafted that if you can reduce the time at all it is better. And I can tell you that it is enjoyable if you cut down the time just a little bit even if it’s not long or problematic initially that you have to wait.

I would have to say that the most time that I would have had to normally wait when loading a Dolby Atmos show from tv/audio off initially, would have been maybe two seconds Max. After the fiber optic cable I would say maybe the Max time might be 1.78 Seconds. But potentially 1.65 max. (I’m just spitball it after like six hours of playing with it).. but definitely enough of a reduction to come here and post about it with a huge smile

upon using the cable everything was working as it should so I don’t know what that means for CEC, But there was not one thing that didn’t work normally

For anyone reading this, three things should be known. The first is that

1. the cable is directional.

2. Some TVs like Samsung have a setting to increase throughput for some HDMI slots, i made sure to enable that settings for the E-arc HDMI, and while mine works perfectly, I cannot say that it would without this setting being enabled. 
   3. fiber cables can’t be bent because they are easily destroyed in this manor. Careful handling is necessary 

After 8 hours of use, I found that I got one or two little hiccups, which normally did not exist. So not perfect, but I suspect that it’s worth investigating further. I use a Samsung frame which uses a “one connect box”, Known to be often finicky with cables and Data transmission. This very well could not be a thing on normal televisions. But I will investigate further