Specifications

Revision 2.4 WebRelay-Quad™ Users Manual
MTU Setting
To change the MTU, manually enter the advSetup.html (case sensitive) page into the address
bar. (http://192.168.1.2/advSetup.html). This new setup page will have a text box that will allow
the MTU to be changed. The valid range is 256 to 1476 bytes. MTU is a network parameter
that stands for Maximum Transmission Unit. This defines the max size, in bytes, of the TCP
packets sent out from the device. This normally can be left alone, but there are some
circumstances where it might be beneficial to change it. One of these circumstances is when
the device is to be used over a VPN (virtual private network). VPN's add extra information to
TCP packets, if the new packets are too big to physically travel across the network (greater
than about 1500 bytes) then the packets will be split up. This causes problems for some
firewalls and those firewalls will just discard the packets. To fix this, the MTU can be adjusted
until the TCP packets do not get split up.
2.4.3 Password Setup Page
The password setup page is used to change and enable passwords. A password is required for
the setup pages but is optional for the control page. The password is enabled or disabled for the
control page by using the Yes or No radio buttons. Enabling the control page password also
enables the requirement for a password when reading/writing XML pages. Enabling the control
page password also disables the ability to communicate with WebRelay-Quad™ using Modbus.
Note that when the password is changed, the password may be displayed in the browser’s history
in clear text. It is advisable to clear the browsers history after setting the password. Passwords
may be up to 10 characters.
Xytronix Research & Design, Inc. page 24