@gokey27 Ok, may have found a solution - bottom line, its NOT connectivity related.

Step 1 - Verify Game Files in the UPlay client. Go to your Games list, click the arrow for More Actions. There will probably be no issues here, but a necessary step.
Step 2 - Reopen the game, it will reinstall DirectX Runtime.
Step 3 - Check the game news in the bottom right of the opening menu, if these have a red exclamation point (error) over them go to Step 4.
Step 4 - Quit UPlay completely and reopen it. For some reason the UPlay client will not discover there is an update until its completely closed out and reopened. Welcome to playing with UPlay.
Step 5 - Download the game update. You may have to find your game folder again (a step we had to do), just find your game directory (Ubisoft > Anno 1800)
Step 6 - After downloading the update, reopen the game and they should be able to connect to the game.

This fixed the error message for my wife - we can now play multiplayer again. Hope this helps someone. Don't go to https://www.ubisoft.com/en-us/help/anno-1800/connectivity-and-performance/article/troubleshooting-connectivity-issues-in-anno-1800-pc/000061883 you'll 100% waste your time. These are troubleshooting problems for connection errors in the 90s.

@gokey27 Ok, may have found a solution - bottom line, its NOT connectivity related.

Step 1 - Verify Game Files in the UPlay client. Go to your Games list, click the arrow for More Actions. There will probably be no issues here, but a necessary step.
Step 2 - Reopen the game, it will reinstall DirectX Runtime.
Step 3 - Check the game news in the bottom right of the opening menu, if these have a red exclamation point (error) over them go to Step 4.
Step 4 - Quit UPlay completely and reopen it. For some reason the UPlay client will not discover there is an update until its completely closed out and reopened. Welcome to playing with UPlay.
Step 5 - Download the game update. You may have to find your game folder again (a step we had to do), just find your game directory (Ubisoft > Anno 1800)
Step 6 - After downloading the update, reopen the game and they should be able to connect to the game.

This fixed the error message for my wife - we can now play multiplayer again. Hope this helps someone. Don't go to https://www.ubisoft.com/en-us/help/anno-1800/connectivity-and-performance/article/troubleshooting-connectivity-issues-in-anno-1800-pc/000061883 you'll 100% waste your time. These are troubleshooting problems for connection errors in the 90s.

@jayzee008 welcome to UPlay... I'll just say, it doesn't get any easier. Just wait until you have a connection issue in game... they'll forward you to a generic connectivity troubleshoot that you would have seen in the 90s (like port forwarding, flushing DNS, resetting router, etc.). Why a game these days still have issues like this is beyond me... I agree, the platform is a joke. If more people used it there wouldn't be a sale on everything almost 24/7.

@gokey27 Also after trying matchmaking it will show "Match Found!" but it will not join the game lobby. It just sits on that screen (no errors or anything).

Hello, I've been playing Anno 1800 since initial release. My wife and I booted it back up for a multiplayer session and we're both getting the LR05 error. We have not changed ISP, modem/router, computer or connection. I've yet to find anything online about what error LR05 actually means. Can anyone tell me anything other than its "connectivity related" and the cookie cutter try doing x,y,z that has been there since the game released? Looking on Reddit, there is another person having the exact same issue - posted today.