Looks like there's an interaction with another mod causing a crash.

Error while running event fiber-optics::on_entity_destroyed (ID 160)
fiber-optics/lib/context.lua:136: table index is nil
stack traceback:
fiber-optics/lib/context.lua:136: in function 'set_entity_context'
fiber-optics/lib/context.lua:146: in function 'cleanup'
fiber-optics/scripts/oc.lua:280: in function 'func'
fiber-optics/lib/tools.lua:50: in function <fiber-optics/lib/tools.lua:46>

Thank you for reporting. I think I have a fix for this already.

please try the 0.0.2 release. It is still a bit unpolished but should fix the problem.

The good news, it doesn't crash anymore. the less-good news, no signals seems to be getting through.

This implies that your OCs are connected to separate power networks. Weird, this is one of the pieces that has not given me grief so far.

Could you try this blueprint:

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

Nope, no luck with the circuit in the blueprint

ok, thanks. Do the connector LEDs turn green? If not, do you happen to use the editor? If yes, you need to turn on time, there is a ticker process that updates the internal state that must run.

With the 0.1.0 release, you can turn on debug mode (mod settings / map), which will log into a logfile (factorio-home/script-output/fiber-optics/framework.log) information about the connectors and the network. If the LEDs turn green and time is passing and still no signals are moving, please turn on debugging mode, let it go for a few minutes and then send me the log file (as a github gist or so).

I was testing the circuit in a creative save, so time was definately ticking with out the leds changing. I'll get a log capture shortly ... but I've found another issue that breaks my dedicated server which i need fix first before my friends turn on me :)
(edit: oh just noticed there's 0.1.0 release i'll have a look at that be first)

https://gist.github.com/badmonkey/902bb54aa50247ed50c191852d2afac5
logs, plus comment with screen shot link

thanks, this is great. The interesting piece is that the log does not contain any lines like this:

24:48:46: Network Id: 1195/1, connected entities: 3
24:48:46: Entities: 14381, 44730, 44596
24:48:46: Network Id: 1169/1, connected entities: 2
24:48:46: Entities: 44686, 44730
24:48:46: Network Id: 1581/1, connected entities: 2
24:48:46: Entities: 44514, 44596
24:48:46: Network Id: 1784/1, connected entities: 0
24:48:46: Entities:
24:48:46: Network Id: 1785/1, connected entities: 2
24:48:46: Entities: 45929, 45919

which are emitted by the network ticker. Those show up only once a minute, so you may need to let this run a bit longer. It seems to me that somehow the OCs got disconnected from the internal network entities. I noticed that you use krasotorio, I will try with that as well.

Out of curiosity: Is this on nauvis or another planet?

I deleted all the connectors and re-add the two needed for the circuit to ensure a "clean" state, still not working.
https://gist.github.com/badmonkey/2733c29ed8b93bda38c2a1857a90fbd7

it's a pretty mod heavy save (sek2bz+) and it was nauvis.
when i get some time i'll start a vanilla+fiber-optics save and see if that's different

still occurs on a map with just fiber-optics.

debug-fiberoptics.zip is a minimal save with the issue (or itll just show where i messed up :-) )
https://drive.google.com/drive/folders/1xjIewJztt8WLFGV9qI64GrIgymN7Ubsj?usp=drive_link

I have a fix and the next version should also fix the existing maps.

ok, I think 0.1.2 fixes all the problems (0.1.1 does, too but the pin coloring is off)

Please try with this blueprint:

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

I havn't tried the blueprint but loading my previous debug save worked first time.