How to disable remote management when IP address is told 'invalid'

[AVinNC]

Traffic slowed - checked logs - DOS attacks, Ping of Death, etc.  Remote user login.  Changed router password, changed Wifi passwords (WPA2-PSK).  Checked devices, which from time to time iphones show different IP.  

When I try to change remote management to only this computer, by giving it the ipv4 address, it tells me invalid IP.

Thanks

[antinode]

> When I try to change remote management to only this computer, by
> giving it the ipv4 address, it tells me invalid IP.

   What/where is your "this computer"?  _Which_ "the ipv4 address"?  As
usual, showing actual actions (commands) with their actual results
(error messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.

   "Remote Management" refers to access from the outside world, not from
your own LAN.  If you're trying to limit access from devices on your own
LAN, then the "admin" password is the only obvious mechanism.

> [...] Remote user login. [...]

   Again, showing the actual message might be more helpful.  Copy+paste
is your friend.

[AVinNC]

HI and thanks for you quick reply.  Desktop computer connected to Spectrum cable through ethernet using C3700.  I am trying to block external computers outside my immediate home from connecting, as the router log indicates they are doing.  It seems I can only attach 1 image at time so here is some visual.  Any help appreciated.

[antinode]

> [...] C3700 [...]

   So, not this?:

> Model: CG3700EMR-1TDNDS|Cable Gateway Docsis 3.0

   "0.0.0.0" is not a real IP address, let alone an outside-world
address.  I don't know what it means in this context, but I doubt that
it indicates anything external, friend or foe.  You may be attributing
more significance to these log entries than they deserve.

   And, as suspected, you're trying to specify a LAN IP address for
Remote Management, which is not allowed (because it's a nonsense).

[AVinNC]

??? -- Yes 0.0.0.0. is ME!  I am logging in to check logs and manage the router.  Do you not see the SYN Flood attacks, ping of death and multiple others on the router log?  it certainly isnt my imagination.  I rebooted the router and when I went to log back on, I had the following message (attached).  Someone else was on remotely and when I logged on i kicked them out.  Anyhow -- scrapping the netgear modem.  This is a known issue and have seen it on many other threads, none of which were seem to have been fixed.  My only recourse is to block all new devices from connecting and curate a small list of known things in the house

[antinode]

> [...] Do you not see the SYN Flood attacks, ping of death and multiple
> others on the router log? it certainly isnt my imagination. [...]

   I see those, too, but a probably insignificant/spurious complaint
from time to time worries me less than it does you.

> [...Someone else was on remotely and when I logged on i kicked them
> out. [...]

   Or the router remembers some previous connection from you.

> [...] have seen it on many other threads, [...]

   Thanks for the helpful links.

> [...] My only recourse is [...]

   Or pay less attention to insignificant false-alarm log messages, and
concentrate on actual problems?