There was a previous ticket here for 1.7 (I think)
Where it seems as though when disconnected from a server/singleplayer, and rejoining, wireless connectors that were in seperate chunks lose their connections. I'm currently playing Stoneblock-2 (1.12.2) and the issue is still occurring for me. The block texture shows a proper connection with it being a green-lit WiFi symbol, but no channels are transmitted unless I replace the Wireless Connectors and re-connect them both together again.

Still happening with the latest version of the mod