Netlink's latest 1.0.35 on their official website won't let you downgrade to any of the generic VSOL fw's. You need to go back to Netlink's own old 1.0.35 (HG323RW_all_1.0.35-200623_NetlinkBsnl_en.tar, available here) and then you can flash any vsol ones. They're starting to remove features...