gm_boreas is a fair bit more demanding than most GMod maps. Try switching to the 64-bit branch of GMod. This will allow the game to utilize more memory, which may fix crashes when you also have other addons that require a lot of system resources. The steps are as follows:

1. Right-click GMod in your Steam library and click Properties
   
2. Go to the Betas tab and opt into the x86-64 branch
   
3. Close the properties and then wait for the game to update

If the above doesn't help, you'll probably have to either reduce your overall number of enabled addons, or find one or more addons that are specifically causing this crash. I would advise first disabling everything else and then restarting the game, so you can get a better idea of the baseline stability and performance of the map. You can then re-enable your addons one by one or in small groups until you identify the cause of the issue.

Originally posted by Blueberry_pie:

gm_boreas is a fair bit more demanding than most GMod maps. Try switching to the 64-bit branch of GMod. This will allow the game to utilize more memory, which may fix crashes when you also have other addons that require a lot of system resources. The steps are as follows:

1. Right-click GMod in your Steam library and click Properties
   
2. Go to the Betas tab and opt into the x86-64 branch
   
3. Close the properties and then wait for the game to update

If the above doesn't help, you'll probably have to either reduce your overall number of enabled addons, or find one or more addons that are specifically causing this crash. I would advise first disabling everything else and then restarting the game, so you can get a better idea of the baseline stability and performance of the map. You can then re-enable your addons one by one or in small groups until you identify the cause of the issue.

Tried these and it somewhat worked, got me to Fully Connected! and then crashed. I'd recommend a more optimized version of the map, like without as many interactive things to cut down on the RAM this map takes up. Thanks!

Are you saying that the crashes still occur even when all other addons are disabled? In that case I'm not able to reproduce the issue. What hardware are you using?

As for modifying the map: I don't have the time or energy to make any more non-essential updates. The source files are free to download, though, so others are welcome to give it a shot.