[Avi]

So, I know I don't go here anymore, but upon searching into this issue as well as someone sharing you were having this issue, I figured I should comment. What I've seemed to have found was having Team Fortress 2 (TF2) installed and mounted to Gmod has been causing this issue; they also mentioned PAC3 may affect this as well. I've never played/installed TF2, so I installed it and tested this myself and crashed upon sending client info to another server. I also had people trying to join that server try to join here, and again they crashed upon sending client info; others that couldn't connect to dinks tried connecting to the other server and again, also had the sending client info crash. TF2 also had a major update yesterday, so that may play into it as well.

But yeah, if you are having this issue, try unmounting TF2 from Gmod. Just to explain how:
Launch Gmod, on the main screen, go to the lower right corner and click the game paddle, there you will see different games. Games that are not mounted/installed have an X next to them. Those mounted/installed have a check mark next to them. If you have TF2, scroll down in that submenu to where TF2 is, and uncheck if it is checked and try joining the server.