Looking for tips on hosting a fun and functional Valheim server.

Valheim is the first co-op game for which I have ever hosted a server. I loved Valheim and was looking for a way to spend time with my adult sons. So I paid for a year of hosting and told them they could invite a couple of friends to join us (everyone is over the age of 25.) I originally wanted to run it with a couple of game enhancing mods but two of our players had to use a cloud gaming service so mods were not possible. We started out playing regularly but as often happens, things tapered off as friction and boredom set in until eventually only one player was using the server – and it wasn't me.

Things started going awry fairly quickly starting with builds near the spawn point. We were all learning but there was no plan, everything was higgledy-piggledy, no boundaries or organization. I have a peeve with high dirt wall enclosures or severely excavated trenches being used as shelter. It's kind of cheating and defeats the point of the game, IMO. I'm cool with moats and/or dirt walls that are low enough to see over (topped with fences, etc. for defense.)

Then some players went very rogue, exploring massive sections of the map, inconsistently marking resources, clearing all the crypts solo, hoarding resources in their own chests instead of contributing to shared ones. Next thing I know, trophies are hung on the stones and we are getting raids that not all players were ready for. We had multiple portal hubs because everyone wanted to make their own. People were changing labels on portals to connect them to their own hub. Some builds were made with massive terrain changes which created lag. Players were logging on with friends I didn't know and turning off their visibility (making it impossible for other players to coordinate sleeping.) The point of the shared server was co-op play but it just wasn't happening.

The final straw was when one player destroyed another player-built structure because of a terrain dispute that I was completely unaware of. The offending player was also completely unaware of the terrain dispute because he didn't see the sign that was hung nearby staking claim to that spot.

I blame myself because I essentially left the kids on the playground without a chaperone. Now that the Mistlands is here, I want to start fresh with some guidelines. Obviously, having no rules is bad but too many rules is bad also. Please tell me what makes a fun co-op server and what helpful rules can I establish before we start again? I am open to allowing QOL mods like Valheim Plus. I ultimately want a fun place to hang out with friends and family…with some really cool shared spaces but also allow every player to create their own structures.