Netgear Router R6020 403 Forbidden after firmware update

[AJBrainslag]

I recently had a firmware update on my router and since the firmware came through anytime I try updating my DNS settings on my router i get a 403 forbidden error and rebooting it didnt fix the issue. I'm currently on Router Firmware Version
V1.0.0.48. I really need to get this set up properly for my network.

[plemans]

If there's an issue after a firmware upgrade, we usually recommend a factory reset and reinstall. Sometimes old settings can cause issues. 

[michaelkenward]

The R6020 is a bottom of the range router. (Surprisingly for something sold in 2017 it has 100 Mbps Ethernet ports rather than the more normal 1000 Mbps .) This section is all about DSL Modems & Routers, very different animals.

It might help if you told people what the modem is in front of this router, if there is one. The model number could be useful. Is it, by any chance, also a router, with a set of LAN ports on the back?

The reason for asking is that a lot of people turn up here trying to put a router behind a modem that is also a router. That can complicate troubleshooting.

You might get more help, and find earlier questions and answers about your hardware, in the appropriate section for your device. That's probably here:

General WiFi Routers (Non-Nighthawk) - NETGEAR Communities

[antinode]

> It might help if you told people what the modem is in front of this
> router, if there is one. [...]

   I don't see how.  A 403 error from the router's management web site
can only be the result of a firmware defect.  It's possible that a
settings reset will stop it from encountering the defect, but I would
not expect changing the device which is connected to its WAN/Internet
port to affect it.  (And, if it did, then _that_ would be evidence of
another firmware defect.)

   If a settings reset doesn't help, then a different (older?) firmware
version might be the only cure.

   Visit http://netgear.com/support , put in your model number, and look
for Downloads.  (For older versions, under Firmware and Software
Downloads, look for "View Previous Versions".)  Find the kit(s).
Download the kit(s) you want.  Read the "Release Notes" file for
instructions.  (In the User Manual, look for "firmware", and,
especially, for a topic like "Manually Upload Firmware to the Router".)
When that fails because of a deficient User Manual, try:

      https://kb.netgear.com/23960
      https://kb.netgear.com/31573