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Re: Home Network Ip Address Question

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Jeff Gaines wrote:
> 
> My new TP-Net Omada DR3650v-4G router appears to have a bit more 
> functionality than the Plusnet Modem 2.
> 
> One is the ability to reserve IP addresses by MAC. In terms of 
> performance is there likely to be a difference between allocating fixed 
> IP addresses to my key PCs and the NAS and using DHCP with a reserved 
> address?

In a domestic environment, generally none whatever.

Problems may arise in a commercial environment where there is a server 
managing DHCP and DNS; and UPS to ensure the server shuts down cleanly 
when there is a power failure.

It follows that when the power returns, the UPS must recharge its 
batteries, then will tell the server to start.  Even it this is quick 
the server itself will not start its DHCP and DNS services immediately - 
it could be several minutes.

Now consider what happens to devices such as printers, NASes, security 
cameras, etc.  When power returns they all start quickly and broadcast 
for a DHCP server - and of course they get no reply.  So they might 
autoconfigure (an address like 169.254.x.y) or not give themselves an IP 
address at all.  So the users can't print and complain bitterly!.

If these devices are all configured with static IP address (so far as is 
possible) then that helps, but it's not the end of the problem.

Suppose the printer is out of commission - powered off for a good 
reason.  The DHCP server might issue the address configured in the 
printer to another device.  When the printer is powered on again, it 
reports an address clash with the other device.  So the DHCP service 
must be configured with a "reserved" address so that it does not issue 
such addresses to any other requester.

In a domestic environment the router will (probably) start quickly when 
mains power is restored.  But the NAS, printer, security cameras etc 
might start equally quickly - so you could theoretically see problems.

The resolution is to allocate a range of address (a scope) in the 
router's DHCP service, and to configure reserved (bound, or other 
similar term) addresses outside the scope, to the devices that must be 
static.  Then configure these devices with those same reserved 
addresses.  So KEEP DOCUMENTATION!

Not all routers give you this flexibility, and not all devices can be 
manually configured correctly.  It's important to specify the default 
gateway so such devices can contact the internet for time services or 
updates.


-- 
Graham J

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Thread

Home Network Ip Address Question "Jeff Gaines" <jgnewsid@outlook.com> - 2026-06-11 16:28 +0000
  Re: Home Network Ip Address Question Andy Burns <usenet@andyburns.uk> - 2026-06-11 17:36 +0100
  Re: Home Network Ip Address Question SH <i.love@spam.com> - 2026-06-11 19:32 +0100
    Re: Home Network Ip Address Question SH <i.love@spam.com> - 2026-06-11 20:35 +0100
  Re: Home Network Ip Address Question Graham J <nobody@nowhere.co.uk> - 2026-06-11 22:08 +0100

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