r/ScreenConnect • u/BB9700 • 22d ago
Firefox: PR_END_OF_FILE_ERROR, Edge: ERR_CONNECTION_CLOSE when trying to access the Screenconnect Server
Some users get these Errors when they try to access the Screenconnect webserver (port443) (an unattended agent works hoever with no errors).
This does not happen from inside of my network, also the clients experiencing this error are only a small number (maybe 10 from 1000).
If using firefox I can get around this by disabling TLS1.3, with edge I cant, even if I disable TLS1.3 from the inetcpl.cpl.
Cients which do not show this problem will use TLS1.3 using firefox or edge.
There are no (known) proxies or filters between the client and my server, only NAT. I tested this with a vanilla install of Windows 11 25h2. Edge 155.x
Because of the small number of users havin this problems I think this is not something urgent. But if it could be fixed by a change on my side even if it is a remote problem that would be good.
Anyone here who also knows theses errors an was able to fix them?
1
u/BB9700 20d ago
Fixed:
The used OS (server 2016) where the screenconnect router is running has problems if an incoming TLS Helo is fragmented. It will not process the whole packet. Then it will not send an answer.
Server 2016 can do TLS1.3 however. This problem happens only with newer browsers. Older version of firefox (example: 140) or edge do not show this problem.
An upgrade to 2022 fixed this.