Some devices randomly losing their IPv4 address

[Kenneth Porter]

On 4/5/2022 2:48 PM, Julien Pierre wrote:
> Unfortunately, the Comcast router's built-in DHCP server cannot be 
> completely turned off. The only thing I can do is shorten the range 
> for its DHCP range, which I have done for its DHCPv4 server. Its 
> DCHPv6 server cannot be disabled, as far as I can tell.
>
> In an ideal world, I would just switch the XB7 router to bridge mode, 
> and use a separate wired router, with working DHCP servers, and be 
> done with it. The main reason I haven't done exactly that comes down 
> to the fact that I have multi-gig service, and can't find an 
> off-the-shelf wired router to do the job. The XB7 has a 2.5GBASE-T LAN 
> interface. I would need a router that has both 2.5GBASE-T LAN and WAN 
> interfaces. I haven't found one, so far. I would need to build one 
> myself, and it would come at significant cost, both in terms of 
> hardware and additional power consumption, not to mention how much 
> unwanted noise it might have, whereas the Comcast XB7 is silent.

I feel your pain. That's why I run a router as an "Internet condom" 
between the Comcast modem and my LAN. I run ISC on an internal server. 
(I'm still having trouble getting the router to pass the IPv6 stuff 
through.) I also started using the Kea server at home, but still use ISC 
at the office. (Kea might be a better choice for a reservation-heavy 
system. I suggest setting it up alongside and temporarily disabling the 
ISC one to test. It should be easy to migrate just your config file, 
since with all systems handled by reservations, you don't need to 
migrate a lease file. Use the keama command to convert your config file.)

I'm only buying the 300 Mbps tier, which most current routers can 
handle. Why do you need 1.2 GBps? Is it something that fq_codel or cake 
can't handle? It's my understanding that the current Comcast modems 
enable good bufferbloat mitigation so the connection sharing should be 
pretty good with multiple bandwidth abusers running. So one should be 
able to have multiple gamers and meetings at the same time at the lower 
speed. Good way to save some money, too.

On the DHCP client problem, have you seen anything interesting in the 
client logs when they should have renewed and gotten a new address? 
Recall that a client is supposed to renew its lease when 50% of the time 
has passed, so it should have attempted a few times before giving up.