How to get time to pass faster on another planet compared to earth?
I'm developing a story where humans colonize a few planets. One planet, lets call it Planet A, has similar gravity to earth, air pressure, and solar radiation. You cannot however, walk on the surface of Planet A with out a space suit, and there is no life, nor most of the essential ingredients. Planet A is arbitrarily far away from earth, it could be in the same galaxy, or across the universe.
Planet A relies on Earth for resources. 275
One day the means by which both communication and transport of those resources stops working (could be wormhole for example), to which the residence of Planet A, after a very long period of time, get the means to travel to earth working again, and travel to Earth.
Part of my story relies on the time between the communication blackout being different for the Planet A side of things, and the Earth side of things, with Planet A experiencing a significant time difference compared to how much time has passed on earth (factor of 2x to 10x longer on Planet A). Note however when Earth's solar system and Planet A's solar-system are connected their clocks are synced or approximately the same (ie time passes at similar rates on both sides). The process of synced time is handwaved, you do not have to explain why it happens.
Is there some sort of scientific explanation for how this could happen? I'm willing to handwave the method of transport between these two far off places, but I'd like to explain the time difference scientifically.
Note, this question is similar to https://worldbuilding.stackexchange.com/questions/84410/can-time-move-faster-on-another-world but I do not consider the following to be valid explanations:
* Time travel, as in someone purposefully made a time machine to go back in time.
* Extremely rare and unlikely occurrences that we've never actually experienced and don't have a real reason to expect they exist naturally (ie a planet moving at 10c and negative gravity...)
* Planets and solar systems that were purposely manipulated to speed up time.
This question (and the answers) also don't appear to take the distance between planets into effect, and talk about two planets in general where mine requires earth to be slower planet, so you can't put earth in a massive gravity well or something unless that's plausibly already the case. Finally my question talks about a hand-waved method to connect the two places with "something", which could provide more ground to expand the possible answers since this "wormhole" can be softer science and aid in answers. 302