[Discuss] RCN dhcp problem fixed, root cause a mystery

[Jerry Natowitz]

So the problem I was having where neither of my two 
previously working wireless routers could get a DHCP response 
from RCN cable modem has been fixed. 

I needed two things: 

1) Time. I really did need to power off everything for 20 minutes. 
2) Isolation of the RCN provided Actiontec MoCa bridge. 

The later is of interest. When I was talking with RCN's tech support on Sunday, 
I made the mistake of not making a map of how things were interconnected 
(or the far easier step of taking a bunch of photos). One of the things I ended up 
doing was removing a little gigbit switch, because it only had two active ports: the MoCa bridge 
and the wireless router. 

Well, it seems that the MoCa bridge does something when plugged directly into either 
of my wireless routers that it does not do when a wired switch is placed between them. 

I told RCN about this, but the tech had no idea why that mattered. 

Anyone have any ideas? I could try seeing if wireshark can pick up anything on the switch. 
BTW the problem with the routers is not just dhcp on the WAN side, they are unable to deal 
with any traffic on the wired side. Wireless seems to be unaffected.