Problems

1.  After installing RHEL on the LEC-2310, why are there only 4 serial ports detected?
2.  After installing Debian on the LEC-2310, why are there only 4 serial ports detected?

Solutions

For Red Hat Enterprise Linux (RHEL)

RHEL only supports 4 serial ports as the default system configuration. To have more than 4 serial ports on the system, you should configure the grub file according the following instructions: 
1.  /etc/grub.cfg a kernel parameter 8250.nr_uarts=6.
2.  #vi /etc/grub.conf
3.  kernel /vmlinuz-2.6.32-279.22.1.el6.i686 ro .... 8250.nr_uarts=6

For Debian

Debian only supports 4 serial ports as the default system configuration. To have more than 4 serial ports on the system, you should configure the grub file according the following instructions: 
1.  /boot/grub/grub.cfg a kernel parameter 8250.nr_uarts=6.
2. Edit /etc/default/grub; GRUB_CMDLINE_LINUX="8250.nr_uarts=6"
3. Run update-grub.
4. Check /boot/grub/grub.cfg
5. Reboot.