Can't change DNS servers on Netgear C6300

[bradleyakapatty]

i'm trying to change my DNS Sever to work with my raspberry pi 4 but i keep getting this error  "internal fail! fail to make the requested change"
why can't i simply change this?!

C6300 
Firmware Version

V2.01.26

[FURRYe38 · Accepted solution]

Well all FW for Cable ISPs has a hand in wnat NG gives them so ISP may have there own modifications before pushing out to users modems. 

One reason why I prefer modem only units then install a external wifi router. More control over what ISPs don't need to have. 

[antinode]

> Model: C6300|AC1750 Cable Modem Router Docsis 3.0

   C6300[v1] or C6300v2?  Look for "Model" on the product label.

> Can't change DNS servers on Netgear C6300

   "Can't change DNS servers" to _anything_ else, or only to some device
on your LAN?

   Netgear router firmware on multiple models has been reported to be
unwilling to accept a DNS server with a LAN-subnet IP address.

   I'm unaware of a work-around.

[bradleyakapatty]

its the C6300 V1 Because it doesn't say V2
and if thats the cast i guess i wasted  $200 on this piece of S***!

[FURRYe38]

Disconnect the COAX cable from the modem. Factory reset the them and setup from scratch. Go in with a PC and web browser and see if you can change the DNS addresses. Sometimes DNS maybe controlled by the ISP and they put restrictions on this. Review the user manual about changing DNS addresses. 

[bradleyakapatty]

ill have to try this on the weekend because i work form home right now.
i really should ask if anyone knows about raspberry pi 4 and pi-hole? because this is my main goal to get this running an working correctly and wish i knew more about networking because this part is killing me.
ill keep in touch on my status too.

[antinode]

> i really should ask if anyone knows about raspberry pi 4 and pi-hole?

   In some cases, describing the actual problem which you are trying to
solve can be helpful.  If I were doing a forum/Web search for relevant
material, for example, I might include "DNS" and "Pi-hole" in the search
terms.  ("Raspberry Pi" is not as important as "Pi-hole", and I would
not expect that including "4" in such a search would be helpful.)

   Answering questions posed here might also be helpful.  For example:

>    "Can't change DNS servers" to _anything_ else, or only to some device
> on your LAN?

   If it won't let you make _any_ changes (like, say, to "8.8.8.8"),
then that's a different problem from not accepting a LAN-subnet address.

   "Can't" is not a useful problem description.  It does not say what
you did.  It does not say what happened when you did it.  As usual,
showing actual actions (commands) with their actual results (error
messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.

   On the bright side, you did include the error message in your first
post.

[bradleyakapatty]

i already said i get error "internal fail! fail to make the requested change" 

[bradleyakapatty]

i try to reset it like you said and no help on that when i went back and try to change the DNS sever i still get the same error "internal fail! fail to make the requested change" 
so there so far it stil won't, cannot, nor let me change the DNS sever

[antinode]

>    On the bright side, you did include the error message in your first
> post.

> i already said i get error "internal fail! fail to make the requested
> change"

   And you're arguing with whom?

> IMG_20200706_192657%20(600x800).jpg

   Note that the picture which you attached (twice?) shows a different
error message, and only you know what you put in to cause it.

[FURRYe38]

What DNS address are you trying to input? 

Seems the modem isn't liking the address as it's saying it's an "invalid address". 

---

@bradleyakapatty wrote:

i already said i get error "internal fail! fail to make the requested change" 

---

[bradleyakapatty]

Yeah I even reset it twice and same issue again with the error like i said.
 But pi-hole gave me is IPv4  192.168.0.61 like the pic shows that i uploaded.
i'm suposed to use the IPv4 and set to the DNS server but thats my issue, that can't change it
 -set it to the 1st DNS Server(or both lines same IP) click apply, "internal error" or "invaild IP address" 

[FURRYe38]

So what happens if you input default ISP DNS that comes down from the ISP? 

Possible that this model modem doesnt' support LAN Side DNS addresses. 

[bradleyakapatty]

when i try to change it, i get the error and it just does back to its default IP. 

209.18.47.63

uploaded pic the default gives me 

[FURRYe38]

Is that someting that comes from your ISP? 

Wondering if this modem modem and your ISP have DNS locked in. 

[bradleyakapatty]

I guess so, it's what default settings go to. I never change anything but both WiFi name's and everything else is by default. And if I call spectrum about DNS server I'm sure they will be clueless and have no idea what I'm talking about. But I guess I'll try.

[bradleyakapatty]

You could be right about ISP. If I'm right the firmware version is from my ISP so could be locked from them like you said😒

[FURRYe38 · Accepted solution]

Well all FW for Cable ISPs has a hand in wnat NG gives them so ISP may have there own modifications before pushing out to users modems. 

One reason why I prefer modem only units then install a external wifi router. More control over what ISPs don't need to have. 

[bradleyakapatty]

i just got back from spectrum my ISP and i'm not 100% they knew what i talking about because the lady just looked something up and said we don't block anything your DNS thats on a server. but i guess netgear c6300 is just piece S*** and ill either buy another modem or wifi router thats not from netgear. 

[FURRYe38]

Good Luck. 

[bradleyakapatty]

Thank you for your help as well 👍

[antinode]

> i just got back from spectrum my ISP and i'm not 100% they knew what i
> talking about because the lady just looked something up and said we
> don't block anything your DNS thats on a server. [...]

   Sounds to me as if the agent didn't understand that the problem is
not with DNS itself, but with setting the DNS server option on the C6300
modem+router.

   The question is not whether their network is blocking anything (DNS),
but whether their provisioning of your C6300 prevents you from changing
its DNS server settings.  Some low-level support flunky may not know
this, so you got the answer to some other question, instead.

> [...] i[']ll either buy another modem or wifi router that[']s not from
> netgear.

   A cable-TV-type ISP has an amazing amount of control over the devices
which are connected to its network.  Much of that is related to DOCSIS,
not Netgear, so I would not bet that changing vendors would help.

   Changing to a separate unit for the cable modem might help.  The DNS
server choice is a router question, not a modem question, so a separate
router would be more immune to goofy ISP policies limiting its options.