For us it's a similar problem, but worse i am a user on the server and I can build the beams fine, fire them, but they do no damage(client or server). The owner also said he could not see or hear the beam fire so similar problem maybe?

We did try reseting the server as i ran into a different problem testing it in singleplayer which was fixed with reload, but no luck that time. I imagine it might be one of the 39 other mods which includes both types of shields 1 npc mod and 2 other energy weapon mods.

the power slider would reset to zero watts but it felt more random than repeatable like in your case. Thanks for sharing your issues, in the time being ill work on making a rotor gun which doesn't kill me 3 times

I can build them fine, but no multiplayer damage. I even hear the death the beam wants to deal. Like I feel like an alpha beam that doesn't even scratch a hair.

additionally we have had the server crash when deleteing the ion beam combiners so well keep watching it since it seems like it needs more time in the oven

The laser slider isn't syncronized so my friend can use the same system seperately and if he fires there is no damage because the host doesn't get the informations of the slider. The host can use the laser as in singleplayer but the other people can't see the laser, the loading and the sliderchange. So only the host can use the lasers and the users can simulate it without damage

So after thoroughly testing this on our server, this is the DS behaviour:

The server counts as singleplayer host, so everything Player A does with the lasers is visible only to Player A.
Players can individually power up the lasers, but their view will be desynchronized, seeing the laser fire at different moments.
The laser do not deal damage, since Player S, The Server "Host" has not changed anything on the lasers output.

This changes when copy&pasting an active laser system. Upon pasting the active system, the host (Server) knows that the system is active, and the laser WILL deal damage.
Upon changing the settings on this pasted laser grid, the view of the players will again desynchronize, this time with the server.
This results in the laser dealing damage invisibly, as the shots for the server go off at a different time than for the players, and only the servers timing is relevant for damage.

Once a grid has been copy&pasted, it can be used semi-effectively, since just turning the laser generators (or the entire grids power) off and on (NOT reducing the output to 0MW, this is without effect) synchronizes the behaviour for server+players and keeps the damaging capabilities.