I wondered the same for a long time but concluded that those 8.6 servers were not as good as we remember them its just that at the time we didn't have anything better; it was either one of those 8.6 that was online or real tibia that started to lose grasp on what player base wanted (world transfers, running pvp, etc)
1. Those servers back in the day lasted longer because you didn't have any other option to play, there were only handful decent ots (without major bugs) running over the course of the year.
2. I would love to play 8.6 again don't get me wrong, but I think after 10 days of elfbot, tibia auto etc I would lose my mind and never log in again with all the scripts for anti-push, auto SSA, ring, auto push, combo bot, etc...
3. Owners want to profit as with everything these days, which I understand. All the games in the last 10 years turned from focusing on gameplay to maximizing profits. So it suits the owners when servers die every few weeks, they can shut it off and repeat the same process in a month, if they lasted longer they would actually have to keep improving and upgrading their product which they hate.
I feel 8.6 could work but with constant updates and things you can do without bot like dungeons, warzones, bosses etc, because if you only botting it gets boring really quick...
But I feel you, options in regard of tibia are really limited, you have:
1. Cipsoft tibia, that has nothing to do with those earlier versions of tibia, it's just a different game now. Yes it's fun at times, it had a lot of QOL changes and updates, but at its core its a boring game where most of the time you if you want to be relevant you have to do boring AOE teamhunts.
Yes there are ways to have fun, play ironman as someone said, or just make new char from 0 and have fun for few months-years by getting all the old milstones like level 100, 200, doing some old quests like poi, inq, etc. But its an easy game for sure with shop and unlimited cash.
2. Medivia, it differs from tibia quite a lot in graphic now, but you can download old packs. But it has the old tibia feel to it with decent and quailty upgrades don't dont focus on maximisng your exp with boring AOE hunts, but actually has decently fun quests, fractions, hard hunts and monsters and etc.. And now with the world with hotkeys there is a little bit of everything for everyone.
3. Tibiantis for complete hardcore gameplay and feel, for me its honestly boring in 2022.
4. Dura similar to Tibiantis but at least has some unique mechanics and events.
5. 8.0 server Kasteria, Realeara, Olders, etc --- Only fun if you play with a big team for war, or if you have like 10 of your friends so you can pk/war with smaller teams that also play there, outside of that it gets boring pretty quickly. Everything has been done for 100 of times now inluding getting level 100-200, poi, inq, etc..
6. You have fully custom serers like We Are Dragon, Midheim etc, if you want to test something new and unique.
7. Hot in the momment like tibiascape, soul of elysium right now, basically a old tibia server that borrows heavily from other games in a lot of elements but still in its core its tibia, they usually last several months, but small percentage of playerbase stick longer...
So there are options, but it all boils down on what you prefer. The fact is you can't go back to 2009-2012 and play shadowcores, helgot, etc, because it's just not possible.