# \_Failed to connect to server 127.0.0.1:4100

**URL:** <https://discourse.slicer.org/t/failed-to-connect-to-server-127-0-0-1-4100/15095>\
**Category:** Support\
**Created:** [December 16, 2020, 1:34pm UTC](https://discourse.slicer.org/t/failed-to-connect-to-server-127-0-0-1-4100/15095 "2020-12-16T13:34:51Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![DimaLat](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dimalat/32/9202_2.png) [@DimaLat](https://discourse.slicer.org/u/DimaLat)\
**Post date:** [December 16, 2020, 1:34pm UTC](https://discourse.slicer.org/t/failed-to-connect-to-server-127-0-0-1-4100/15095/1 "2020-12-16T13:34:51Z")

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Operating system: Windows 10  
Slicer version: 4.11  
Expected behavior: Matlab bridge executes Matlab properly  
Actual behavior: There is an error calling Matlab

Debug: In D:\D\P\S-0-E-b\SlicerOpenIGTLink-build\OpenIGTLink\Source\igtlClientSocket.cxx, line 67  
igtl::ClientSocket(0000028AAE0E1B30):  
Failed to connect to server 127.0.0.1:4100

Waiting for Matlab startup … 59sec  
ERROR: Cannot connect to the server

I’ve tried this one:  
_netsh firewall add portopening tcp 4100 MatlabBridge_  
and it still not work  
Then i tried a new one like:  
_netsh advfirewall firewall add rule name=“MatlabBridge” dir=in action=allow protocol=TCP localport=4100_  
and it is not help.  
Please help, may be somebody know the sollution of this error?

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**Author:** ![Mehri\_Mehrnia](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/mehri_mehrnia/32/15447_2.png) [@Mehri\_Mehrnia](https://discourse.slicer.org/u/Mehri_Mehrnia)\
**Post date:** [May 30, 2022, 1:15am UTC](https://discourse.slicer.org/t/failed-to-connect-to-server-127-0-0-1-4100/15095/2 "2022-05-30T01:15:35Z")

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the port is blocked by firewall probably. after I changed the Windows I got the same issue.