i have rb450g
after some problems i found the lan cards read 10mb not 1000 and the internet speed is so slow then i found every lan port appear tow times when connect to lan found twice mac address i think there is virus and start to reinstall the rb from net-install i started to make boot but the router refuse to boot from Ethernet (mistak was from ether5) but ir refused i tried much times and last time i mistake the order and give it order to format nand storage then i think to transferred files to nand the terminal gave me tow choice transfare file to nand from XMODEM and then i stoped caz iam not know the XMODEM transfage files i found on guide of router board itself this comment .
upgrade firmware – receive a new boot loader image using XModem protocol over serial line or using
DHCP/BOOTP and TFTP protocols through the Ethernet network (upgrade firmware over ethernet | upgrad
firmware over serial port).

this is first time to net-install and not know any information about xmodem transfare files any one can guide to to do that and hope to know which file will transfare to nand and where i put this files and how do that

please help me to do that my network stop and could not do any thing
give me any wiki guide or any text file help me to transfare files using xmodem
please SOS