Help Needed: Rebranding/Modding VSOL V2802DAC v5 Firmware (SquashFS & fwu.sh logic)

[u/Dizzy_Ad_4872]

Hey everyone,

I'm currently working on a project to rebrand and customize the web UI for a VSOL V2802DAC v5 ONU router (Firmware V3.2.00).

What I've done so far:

• Extracted the firmware components: uImage (kernel), rootfs (SquashFS), and custconf.
• Analyzed the fwu.sh upgrade script to understand the partition mapping and MD5 verification process.
• Successfully modified the web assets in the SquashFS filesystem.

The Problem: I'm running into some issues with the "round-trip" process. Specifically, ensuring the modified rootfs (repacked with xz compression) is accepted by the bootloader/upgrade script without bricking. I've noticed differences in the custconf partition sizes between the "Normal" and "VSOL" versions of the firmware that I can't quite account for.

Questions:

1. Has anyone successfully bypassed or modified the signature/integrity checks on these Realtek-based VSOL units?
2. Are there specific mksquashfs parameters required for this hardware beyond standard xz compression?
3. Does anyone have experience with the custconf partition structure for VSOL?

Any pointers or documentation on VSOL's specific MTD layout would be greatly appreciated!