I'm facing this strange problem.

I've a branch location connected with 2 ISPs on MPLS (See attached Image). The location have mixed OS PCs (Windows & Ubuntu, major chunk is of Ubuntu)

Whenever ISP-R goes down, I switch the location to ISP-S. Now the problem is in windows PCs after changing over the ISP things work fine.

In Ubuntu PCs, the trace-route still goes to ISP-R. Also, in one instance the first packet goes to the gateway ( in other it goes to (

If the network is disable and then enabled again it starts working.

Due to this major users are not able to connect to application from HO. See below:


  • Any help in this issue.
    – Ajay Bohra
    Oct 11 '17 at 12:42

Well I found the reason it was due to MSS size in ISP router WAN Interface.

I logged call with ISP and they set the TCP MSS to 1450. Things are working smooth.

but still one thing is strange the TCP MSS didn't affect in Windows but Ubuntu was having problem.


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