I seem to have experienced a similar issue as @Aayush_Kedia and @Chakshu_Gautam.
Neither the work around proposed by @Sandeep_Prabhu1 or @yanokwa seems to work.
I have however backed up the central server and restored it on an AWS free tier and I am able to preview forms form the web. Assuming it has something to do with the organization server I am running central on.
I am thinking of trying increasing the CPU & RAM as @LN suggested though I doubt that this is the issue.
Any help pointing me to a solution will be much appreciated.