Depending on what server you are playing on, this could be due to the account limiting that many servers use. Basically, we only allow 1 character to be logged in per account at a time. So, if you have more than 1 character that you want to play, make sure they are on separate accounts. Otherwise, the character already logged in will get booted when the second one logs in. Not all servers use this setting, but many do.
If you are using 2 separate accounts already and having this problem, maybe your issue is something else.
And, welcome to the community! It is always nice to see new faces here
