Everything Old is New (STO)
From Trekipedia
Obviously, the Devidians have found a way to harness this surge of triolic energy. The existence of the Devidian portal means they're traveling freely between the station in the present and the past.
Since 23rd century technology can't detect the Devidian phase-shift, this time period is rife with potential victims. The only choice now is to stop the incursion at the source.
You'll have to take that portal into the past and find out how the Devidians are creating this new surge of triolic energy. Stop them and find a way back without altering the timeline.
Don't worry about Temporal Investigations. I'll pull a few strings. They'll never know that you were gone. Best to keep your team small, just in case.