"There is a chance of getting him but maybe not as strong as we anticipated at the end of the season," Trollope told BBC Radio Bristol.
"I'm speaking to a number of agents and players and we're hopeful that we're going to be able to secure something."
He added: "We've turned all our attentions to the goalkeeping situation at the moment."
Trollope understands that Reading have been discussing fresh terms with Andersen, who still has a year remaining on his current deal.
"I think his form last year has allowed him to be in a stronger negotiating position for a new contract."
The keeper further enhanced his reputation playing for Denmark in an under-21 tournament in Toulon, where he earned the golden gloves award.
"That's obviously raised his profile and I believe there's some interest from foreign clubs, too," added Trollope.
Source: BBC Sport
Source: BBC Sport