With the theory of relativity currently being much depended on and not being proofed wrong, time is very subjective and depends on the condition of the observer. I suppose what you means is the approximate time that every stationary or slow-moving object tells you it is, perhaps a clock back on Earth. I believe your problem in the question is that photons travel at a fixed speed which seems insufficient for intergalactic synchronization purposes.
This superficially seems analogous to the time delay caused by low network speed when sending or synchronizing data(time, real-time computer game data, video calls, etc), called latency. As implied by the time precision needed by modern activity, time synchronization network protocols have been developed to synchronize time while minimizing latency issues, including the NTP and PTP. However, intergalactic round-trip time is pretty much unacceptable and impractical.
If light cannot solve the problem, it seems like the only way to solve it is the superluminal "spooky action at a distance" as described by Einstein -- quantum entanglement. Quantum teleportation has recently seen some success. Yet, this is just another disappointment: relativity doesn't say nothing can move faster than light. It says no mass or information can move faster than light. We can instantaneously teleport quantum states, but real communication would have to wait, for as least the duration light needs to reach the target.
The final answer, there is still no means of communication faster than light. Maybe warping spacetime might help? Anyway, if your story is Sci-Fi, you could just say that they can create ultra-small wormholes and send information over that. It would certainly drain lots of power though.