So there are lots of discussions about the portals and the devs aren't 100% for them as they limit exploration in a way and can make players miss so much, but at the same time they are a good addition to the game, and can cut down on those boring tasks. Maybe this could be a simple solution..
At the moment to build a portal you need a to use cores, this means players can set up a portal at their "main base", take a the required stuff with them to build a tagged portal, and travel to far off lands. Build a workbench, and then erect a portal and bang, fly back home, grab loads of regents/stuff and port back building a sizable base without even really moving from the coast.
My suggestion is simple… not all portals require cores, each portal requires a unique items from each biome. So cores could be for black forests, and then a different items for lets say the plains, swamps etc that is only dropped from the creatures there and even maybe even a low drop rate.
So if you travel away on your ship, you have to set up camp….survive then you attack the natives, until you get this unique item. You can then build a portal … but it doesn't stop there, the matched portal must also have the exact same unique item for it to function so you are forced to farm another item and then sail back, or take along walk back to a first base.
You could make it then in the meadows you can use any portal type, this would mean that if you wanted to you could still use the cores but only set up portal bases to other meadows, which isn't ideal or always possible. If you had a main base lets say in the snowy mountains for example, you would need a crystal (that current unused ones from stone golems?) but you can only port to other snowy mountains or the meadows. If you want to build bases in all biomes with portal left right and centre, you're going to have to work for them.
On another note, would be a cool idea to be able to set the glow effect for a portal, colour code your portal rooms 😀
Source: https://www.reddit.com/r/valheim/comments/mgl19f/portals/