Q: Packet is often fragmented when MA5200G enables l2tp services. Usually, both tunnel and session could be established normally, but web pages cannot be opened; at the same time, the client cannot ping through to big packets of 1500 but small ones. All is resulted from packet fragments, and it needs to change the MSS value of client. How?
Follow two methods as follows to change MSS value:
1. Use registration list to change the MSS value of client, viz. to change defaultrcvwindow (for how change the registration list, see attachment: Changing Registration List.rar
hkey_local_machine\system\currentcontrolset\services\vxd\mstcp, defaultrcvwindow is the default size of buffer of transmission unit; please change it.
2. Use software to change mss value; for more, see the attachment, Changing Registration List.rar
Use software to modify the mss only, and keep the other consistent. Noticeably, reset the PC after saving the configuration of changes. Make sure if registration list is changed successfully after reset of PC.
MSS is from negotiation, so it relates to the software of client. If L2TP user could ping through but cannot open web pages because of fragments, you could replace the client software to test apart from changing MSS, such as interconnecting dialer of Telecom.