diff --git a/Docs/Modify_Firmware.md b/Docs/Modify_Firmware.md
new file mode 100644
index 0000000..d54e3dd
--- /dev/null
+++ b/Docs/Modify_Firmware.md
@@ -0,0 +1,34 @@
+# Modify
+You need a Linux PC/VM, Ubuntu as Operating System
+
+## Prerequisite
+You need these program installed:
+* `tar` (extract tar package)
+* `squashfs-tools` (extract/repack rootfs)
+* `qemu-user-static` (run MIPS VM)
+
+## Extract firmware
+* Extract Firmware package in `tar` format, we need `rootfs` file
+* Extract `rootfs` partition
+```
+unsquashfs rootfs
+```
+
+## Repack firmware
+* Repack `rootfs`
+```
+mksquashfs squashfs-root rootfs.new -b 131072 -comp lzma
+```
+* Rename `rootfs`
+```
+mv rootfs rootfs.old
+mv rootfs.new rootfs
+```
+* Update `md5sum`
+```
+md5sum fwu.sh rootfs uImage fwu_ver > md5.txt
+```
+* tar current folder
+```
+tar -cvf ../firmware.tar *
+```
diff --git a/Docs/TWCGPON657.md b/Docs/TWCGPON657.md
new file mode 100644
index 0000000..4abb3d4
--- /dev/null
+++ b/Docs/TWCGPON657.md
@@ -0,0 +1,12 @@
+# Flash
+I have been using TWCGPON657 (without fan) for a month and never had an issue, so in this sections, flash V2801F firmware into TWCGPON657 stick and fix auto-reboot issue.
+
+## Steps:
+* Downgrade your TWCGPON657 to version B13 or below.
+* Flash with `V2801F_V1.9.0-201104.tar` and wait.
+* Quickly login and execute `echo 3 > /proc/fiber_mode` to avoid auto-reboot (invalid `VS_AUTH_KEY`)
+* Disconnect fiber from module to restore telnet
+* Update `VS_AUTH_KEY` acording to `ELAN_MAC_ADDR` and `HW_HWVER`
+* Reboot (in telnet)
+* Reflash again with `V2801F_V1.9.0-201104.tar` (must do after fix `VS_AUTH_KEY`)
+* Enjoy!
diff --git a/Docs/V2801F.md b/Docs/V2801F.md
new file mode 100644
index 0000000..706af12
--- /dev/null
+++ b/Docs/V2801F.md
@@ -0,0 +1,20 @@
+# Auto Reboot Fix
+## V2801F
+### Issue
+* Invalid `VS_AUTH_KEY`
+* Changing MAC Address `ELAN_MAC_ADDR` can cause wrong `VS_AUTH_KEY` value
+
+### Fix
+* You need to generate new `VS_AUTH_KEY` when change `ELAN_MAC_ADDR` and `HW_HWVER`
+* Apperently, you have few seconds to access Telnet before rebooting
+* To prevent auto reboot by entering `echo 3 > /proc/fiber_mode` (XPON Ethernet Mode)
+
+> If you can't type fast enough, use this autoit script `quick_telnet-login.au3`.
+>
+> Take a look some generated [`VS_AUTH_KEY` here](VS_AUTH_KEY.md)
+
+### Note
+When `echo 3 > /proc/fiber_mode` is set, you lose telnet acccess, you need to unplug fiber to get back
+
+## TWCGPON657
+* No such problem, `VS_AUTH_KEY` does not exist.
\ No newline at end of file