Based on user reports and changelogs, here is what you can expect:
Historically, D-Link had an open FTP at ftp.dlink.com . The path would be similar to /Consumer/DSL-2750U_C1/Firmware/ . firmware d-link dsl-2750u h w c1
A: No. The hardware is limited to 2.4 GHz 802.11n (300 Mbps PHY). Real-world throughput is ~60-80 Mbps. No firmware can change that. Based on user reports and changelogs, here is
(unofficial)
is a controversial device in the custom firmware community. While it is technically possible to flash using the CFE recovery mode, it is not recommended for modern use: Multiple vulnerabilities in D-Link router DSL-2750U - JVN The hardware is limited to 2
The proliferation of low-cost DSL routers in emerging markets has led to a large attack surface. The D-Link DSL-2750U is often deployed by ISPs (e.g., BSNL in India, Telkom in Indonesia) with minimal security updates. Hardware revision C1 differs from earlier revisions (B1, C) by using a different flash layout and a newer Realtek or Broadcom system-on-chip (SoC). Despite this, firmware analysis reveals that core security flaws persist.