The Windsor Hotel has fallen out of favour with its younger clientele after raising the minimum entry age to its garden bar without notice.
The South Perth pub made the sudden decision to ban patrons aged under 25 from its back bar after anti-social behaviour from some young punters, including a group called "Tommy and his crew".
All other areas in the hotel are open to people aged 18+.
A representative from the Windsor said the pub was forced to take "drastic" action to get the message across to the group of young men, who are believed to be from southern WA and other remote locations around the state.
"We've had this group of young country blokes in our venue for quite some time," the spokesperson said.
"I joined here about 12 months ago and was shocked by their behaviour but let it ride and tried to reason with them, tried to talk to them.
"Unfortunately they refused, they didn't get back to us, so we had to implement a drastic policy to get the message across."
The Windsor has suffered as a result of the ban, with its Facebook rating dropping to 2.4 stars on the back of 157 one-star reviews, most of them posted by young patrons since the age ban was enacted.
It has since removed the option for patrons to review The Windsor on its Facebook page after getting slammed by the low ratings.
"We are definitely not a 25+ venue," the spokesperson said.
"They deliberately tried to decimate our business by listing one-star reviews on our page but all they have done is expose themselves."
The Windsor was expected to release a statement on Tuesday afternoon confirming its new age policy but WAtoday understands entry to the garden bar will now be restricted to patrons aged over 21 but the policy will be reviewed regularly.
"Entry for younger patrons will be managed on the door, on the night... we know who they are," the spokesperson said.
Some of the group's anti-social behaviour was caught on the pub's CCTV cameras and including smashing glasses unnecessarily, causing altercations and other footage "that would embarrass your parents".
"This behaviour I believe comes down to the culture of the drinking in Australia," the spokesperson said.
"They pre-load on drinks at home, and treat their house with respect, then think 'let's go f--k up a venue'.
"Unfortunately the Windsor has had enough of it and we've acted appropriately."
Australian Hotels Association WA has been contacted about the age limit ban.
The Windsor came under fire in July 2016 after WAtoday revealed it was selling pints of beer in schooner-size glasses.
It switched to schooners in two sizes (285ml and 425ml) but its website still advertised it sold tap beer in middies and pints.
When we paid the pub a visit, a pint of Guinness arrived in a traditional 568ml pint glass but a pint of Little Creatures Pale Ale was served in a 425ml schooner glass by the same bartender.