Linked shares in favorites menu finder disappear after connection loss

While developing site's on our local server, I use the favorites menu in Finder to easily and quickly acces various sites. In the ubunutu-server, the /var/www folder is set up as a share. Within this folder there are multiple folders for all sites (/var/www/site1/, /var/www/site2/ etc.). Once connected to the share from ubuntu, I drag the folders of the files I'm currently developing to the favorites menu at the left side of Finder.

However, sometimes (not always) when the server had been down for updates / maintenance (so the share is currently offline), Finder deletes ALL folders I added to my favorites list. It happend today for the third/fourth time. I had about 8 folders linked in the favorites menu in Finder and after a restart, all are gone 😟

Please fix this, it's very annoying!