Do not nerf the xp on dungeons that give it please. I think a lot of other things need a boost instead. I just made a new character with friends, it was frustrating trying to find dungeons that gave XP compared to the investment into them. And a lot of the decent areas are often frequented, so we'd come in to find things at low spawn.
Another issue is a lot of dungeons have resources in them. Like the sullen woods are farmed by people who want the alchemy reagents, leaving it at low spawn if higher levels are grinding out alchemy.
As for locations:
Grimishka caves: You barely from them even at level 2.
The giant winding tunnels under Vallaki/the forest: Very little xp at level appropriate levels. It was still a challenge to take on, especially if black puddings had spawned, but gave very little xp compared to the difficulty. I think all slimes could have their XP amount increased, they are not worth killing for a lot of classes because of the damage they do to equipment, the splitting, the equipment stripping, the unnerfed true seeing, the bludgeoning requirement, and so forth. They're a very difficult creature that have a lot of tricks to them, that gives very little in reward for defeating them.
Random caves: Often didn't give XP to make them worthwhile. Too hard to do at level 2 or 3, but by the time we were level 4 or 5 we weren't getting much XP from it, or no XP at all. A lot of the dungeon content around Vallaki consists of random caves, too. There's something like six random spawn caves that aren't worth doing except for the bandit bounty.
Sullen Woods: The shadow wolves and lesser shadow wolves cast dispel, which makes them impossible at low levels. We weren't even getting decent xp from it compared to the added difficulty that dispel added. The area has shadow rats too, which gave very little xp despite being around things that added a lot of challenge to the area.
Seconding that spiders don't give enough XP for the difficulty.
The hidden trap door fortress on the Svalich road: Much like other random spawn caves, the spiders/ogres/bandits/heaven forbid slimes don't give enough XP versus the challenge. Offhand I want to say that the more difficult random spawn caves (such as on Ghakis or north of the lake) give ok XP and loot. If you can change the fortress to use those spawns instead, it might be a better dungeon. But this is off memory, I haven't done the newer harder random cave spawns in a while.
Ogres on the road: Often at high spawn because nobody wants to kill them. It might be nice to make it worth killing them. There's not a whole lot of them, boost the XP they give so if it actually does get to a higher level spawn it'd be something people passing through could get excited for rather than running through and pretending the ogres don't exist.
Vegepygmies: Terrifying noob trap. Someone I know who tried the server had a negative experience as a noob, they were exploring while invisible and got killed by their unnerfed trueseeing, and left the server. Vegepygmies are sort of difficult and can do a lot of ranged damage quickly, and give absolutely no xp to make them worthwhile. I don't know if this has changed in recent years, it's high risk enough that I don't like going down there. I made the mistake of going down there at low level too when I was initially exploring the server.
People have mentioned the Village dungeons. I think the dungeons are fine, the issue is the xp is not good despite the challenge and the loot is bad. For example, the infamous well dungeon is pretty hard at level-appropriate levels. And the loot is really bad.
The vault at the back of the Village ML church dungeon is really, really easy once you're able to get the key to be able to do it. The shadow fiends in it look like they should be really scary and dangerous, but they're easy and don't reward much xp. And the loot is bad.
I love both of these dungeons, I like that search and exploration are big parts of it. You don't hear people complaining about the other similarly complex dungeons, because it's worth doing them. The only issue with these two dungeons is they have no reward and people feel burned for spending time on them.
The crypt in behind the Village ML church is sort of bad too. Me and a friend tried doing it lately and maybe it was just on low spawn, but he was level 9 and got no XP from it, I barely got anything at level 7.
Otherwise:
Could the xp from woodland critters be boosted to how it was years ago? I was able to get to level 3 off killing deer/mink and turning in hides when I started the server. Right now it's unreasonably difficult for a level 2 to become level 3 unless they get carried by other players or do delivery quests over and over and over. This makes it unintuitive for people new to the server to know what to do unless they have friends who can guide them.
When I say unintuitive, I mean the way you normally think about gaining XP is going and killing stuff or doing dungeons. But it's very clunky until about level 4, and a lot of level 2/3 dungeons don't reward anything. The most optimal way to get XP is to know how the server works, or get carried by friends. Both of these require a pre-established presence on the server. It would be better for new players if things like hunting deer and minks was viable for the first few levels again.
A bunch of my friends are checking the server out and we're trying to figure out the best way to get them through level 2 and 3 so we can start doing dungeons together. I'd like to do dungeon content with them, I think PotM's dungeons are a lot of fun. The server mechanics make going through the dungeons require some thought, preparation and planning to figure out what a group can accomplish with what resources they have available to them.
Another suggestion is to make getting to level 4 or 5 easier, because that's when the game starts to get more playable and enjoyable. When I could go take friends out to low level dungeons, and each class would be able to do some things that their class gets to do.