Getting others to play on your server

[Niwashi]

Well, the restriction is calculated pretty simply, based just on the number of players currently logged in at the moment. If lots of people are already logged in on Exodus, then character creations on it will be restricted until that number drops down below some threshold. This means that any time the number of players is a bit lower than usual (or at least lower than it was last time he tried and was blocked) his chances of getting in are better. So just trying at typically low-traffic times (like very early in the morning on weekdays) usually works.

Other options would be for both you and your husband to create new characters on another server that's not as crowded and play together there, or (if you're willing to spend a bit of money on it) for him to create a character on another world and then transfer either his character to Exodus or yours to whichever world he's on.

(World transfers don't officially bypass the character creation restrictions, but since it's SE's software rather than the player who keeps checking for when the world opens up, it lets you avoid the frustrating "Is it open yet? Is it open yet? Is it open yet?" checking. That makes it effectively seem as though it bypasses those restrictions, and so you can get into any world you want if you pay for the character transfer.)

Personally, I'd recommend the "both of you play on a less crowded server" approach. It's the solution that those character creation restrictions is intended to encourage — to spread out the traffic load, getting more people off of the highest populated servers and onto lower populated ones. How viable that option is will, however, depend a lot on how many other friends you've made on Exodus whom you wouldn't want to leave behind.