Hi DoctorWho788,
To your question:
Is there any way to play the myst 5 ages with a friend?
Play as in visiting, exploring the ages, and enjoying the sightings with a friend: YES
Play as in actually play Myst 5 ages as intended in the solo game: NO
Let's review some facts:
1) Myst 5 End of Ages is really a follow up of Myst URU, it uses the same game engine but it was intended to be played solo in 1st pers mode where Myst URU can be played in 1st pers mode or in 3rd pers mode. In Myst 5 End of Ages you are interacting with some characters and you are encountering some animals.
2) Deep Island is a shard based on a fan hack of Myst URU (an offline game) to make it online, it's an alcugs server. It had is haydays, its development stopped a long time ago. Nowadays we are grateful it works... There are many "offline-online translation" issues, known issues. For example, crabs in Ahnonay are bugged so they were taken out of the Deep Island shard to avoid the bug.
3) Myst 5 End of Ages "addition feature" is a "hack over a hack" so basically there are even more bugs, mostly unaddressed. Almost every "moving aspects" of the solo game have been disabled (Yeesha appearances, Bahros, ability to write on bahro stone, etc.) keeping just the bare minimum (linking possibilities, some animals like snakes & butterflies, day & night shift in a particular age)
So, the addition of Myst 5 End of Ages is really awesome from an exploration point of view but from a playability point of view, prefer the "get together & solve together with a friend experience behind one's computer screen"