The 22-year-old spent last season in Berkshire on loan from Wolverhampton Wanderers, the wide man scored seven goals in 42 appearances.
Now freed from a five-year transfer embargo imposed by the EFL, Rob Couhig's Royals are able to move back into the transfer market with fees.
Campbell, one of the youngest players to ever appear in Old Gold, appears to be available to purchase, with the Royals keen to bring the Wales youth international back permanently.
However, according to Football League World, fellow League One side Stevenage are keen on Campbell.
With at least one year left on his contract, it would take a fee to take Campbell away from Molineux on a permanent basis.
Alex Revell's side finished 14th in the third tier last year, drawing both fixtures with each other.
Campbell's driving run and cross set up Harvey Knibbs for the goal at the Lamex Stadium in November.
Reading are yet to make any moves in the window, but Couhig claims only a few sides have the financial power of the club, who are looking to end a three-year stay in League One and return to the Championship after last year's seventh-place finish.