if you got banned from logging in for some period of time these rules seem to work well to avoid this i copied this from someones post
Part One: how to AVOID Realm Down.
Ok everyone! I guess you have all (without exception) have experienced seeing that annoying message on your character-select screen which says:
"Your connection has been temporarily restricted ...." etc etc
This is called a "Realm Down" for those who do not know, and it was implemented by Blizzard back in 2004.
Pre-2004, when players changed characters too quickly, all what battle.net did was "throw you out" (force log-out), but then all you had to do was click on battle.net and re-log in
Now, if you change characters too quickly, you will eventually get "tagged", and soon you will get a "Realm Down" error, which means that you cannot re-enter battle.net for a random amount of time, somewhere between 30 minutes and 48 hours!
Some people, who do not have static ip (internet protocol) simply reset their routers, and they are again good to go. It's always better to wait 2-3 minutes rather than sit down the whole 30 (minimum, as previously stated) minutes to get back online. While this works quite fine, unfortunately it is not available for all players.
Special note: Neither Blizzard nor it's representatives have stated what the minimum time limit is for creating a game on the Battle.net servers so that such a ban can be prevented by legitmate players, since the new implementation was originally designed to stop people from doing illegal "botting" activity (or running a program that lets your account create games without you having to be at the computer). Blizzard has not provided any sort of remedy for the situation to get legitmate gamers who were wrongfully banned back on the Realms and back into gameplay. However, such "botting" activities have not stopped on the Battle.net servers after Blizzard implemented the changes, since hackers have built programs to circumvent this "Realm Down" message, thus making gameplay unfair to those who legitly play.
So, the best, legitimate solution is to simply avoid getting a "Realm Down" altogether.
But how exactly do you do that?
Due to an extensive amount of "game-research" and playtesting, I have reached an ultimate verdict upon this matter of utmost importance:
Just follow these simple rules, and you should never see a "Realm Down" ever again! I know I don't!
1: When you switch characters, please wait a minimum of 20 seconds on the channel before clicking "Join/Create" game.
2: When in-game, please wait for a minimum of 3 (three) minutes before leaving the game.
3: In case a game fails to create/join, DO NOT ATTEMPT to create/join another game for at least three minutes!!! See also point #4 below.
4: Do not login with more than 20 characters per cdkey per hour (each of these counts as a game toward the 20 games per key per hour rule).
I follow these simple rules, and I haven't seen the annoying "Realm Down" message for a long time!
Hope this helped you.
Enjoy!
SPECIAL NOTE: The above guide works ***only*** if you are running the game "as-is", meaning, no cheats/hacks including, but not limited to, maphack (lite/hackmap etc), project, as well as other 3rd party software you might be using.
I tested the above last night running project, and after changing a few characters, I got a "realm down". Then I reset my router, unloaded project, re-loaded Diablo II, and re-tested the game "as-is".
Guess what: nothing happened
It seems that Project sends some bad packets and floods the server, and that is why people who use it often get "realm down".