Wel... here I I have some sites favorited and others that I've been researching just now...
https://forum.askgamblers.com/ - In my opinion, its the best there are!

https://www.casinomeister.com/forums/ - This is older than the online casino craze, i think having been around since at least 1998.

https://www.casinolistings.com/forum - I donot frequent it... but i see people talkinhg about a lot in some groups.

https://www.gamblingforums.com/ - Thisare favorited here, but I don't think I've ever created an account.... maybe you can test it.

Besides that, I think its worth checking out the Reddit section too, r/gambling which has a large and very active community... there are always good tips that, peoples sharing experiences in a very informal and honest way, i liked it. Also on Reddit is r/onlinegambling, which follows the same theme, but is more focused on online casinos.

Then there are too more focused niches, such as https://forumserver.twoplustwo.com/ which discusses poker strategies, or https://www.roulettelife.com/ which is the same idea but for roulette.

I hope help you!