Modem Mode on Hub 4 won't work - no DHCP/WAN connection (but connection fine in Router Mode)

[mercilesskiller]

Hi All

I've had an issue with my Hub 4 come up overnight which I'm wondering if anyone has any ideas around. 

I have a 500mb Virgin connection which works fine when the Hub 4 is in router mode. It has been operating however in Modem Mode, connected to a Netgear Raxe300 NightHawk with no problem for months.

I woke up this morning with no connection. Hub 4 light was still green. When looking on the Netgear router, there was no IP address coming on the WAN port of the Netgear (DHCP didn't seem to be working). Reset Hub 4, nothing. Tried different cables, nothing, reset Netgear, nothing. Couldn't access the Hub 4 in modem mode through the Netgear because that internal IP (192.168.100.X) wasn't coming through DHCP. 

I manually set a static IP on the WAN port of the Netgear to 192.168.100.13/255.255.255.0 with default gateway as .1 - through this I COULD then connect to the UI for the Hub 4 (success!). However, not the internet... I took some screenshots of the admin page on the Hub 4 but nothing seemed to suggest an issue. Note in the last screenshot there's no IP/WAN information though when in router mode, on this page it does show a WAN connection status.

For now I've flipped it back into Router Mode so accessing the internet via the Hub 4 but I really need to get the router working again in Modem Mode. Any ideas? It almost feels like there's been some firmware update that's broken modem mode? It sounds like for whatever reason when in modem mode, it just won't connect externally nor will it give an internal IP to the Netgear - did plenty of "leaving it off for 2 minutes" and reconnecting but no luck.

Thanks!

[mercilesskiller]

Reuploading the last 2 images without the MAC addresses included 🙂 - Also just to add, I've gone through the process of turning off the hub 4 when it's in modem mode for 5 mins, restarting the netgear to establish the wifi connection, then connecting the cable and turning on the hub 4, waiting 5/10 mins but still the same behaviour. 

I've heard how MAC addresses can "lock" though in this case it was working fine and just stopped overnight. So feels like something changed (a new WAN IP which then for some reason caused everything to fail, or a software update or something else). 

[Roger_Gooner]

Try a PC or laptop connected to the hub in modem mode to see if it works.

[mercilesskiller]

Wow - so I figured something odd out which contradicts most of what I've seen on these forums (spoiler, it's working now). Just before doing as you said @Roger_Gooner, I realised something. Everytime I had reset anything, I made sure that I only ever reset the Hub 4 when my Router was already initialised/working. If I reset the router, I would always have the Hub 4 turned off, then turn on the router, then turn on the hub 4 right? 

That's what the advice everywhere says to do in order to set this thing up. However, the weird behaviour I was seeing is either the link existed (the router detected a cable but no IP address), OR the router wouldn't detect any link what-so-ever even though the cable was plugged in. Weird right? And in that case resetting the Hub 4 wouldn't fix it. 

But I tried it the other way. Rather than resetting the Hub 4 - after leaving that fully initialised, I reset the Netgear router itself with the cable still plugged in etc. When the Netgear came back, it initialised and got the IP address from the link itself. 

Super weird. This seems to conflict with the instructions provided on the correct routine/way to initialise. Even on the router when forcing DHCP release/renew it wasn't picking up the link/IP but when restarting the router itself it worked. So now I'm wondering if it maybe a router compatibility issue with the Hub 4 (although not sure how a hardware compatibility issue would cause this behaviour). 

So I guess all along the Hub 4 was connected to the internet, but for some reason it wouldn't pass an IP down to the netgear when the Hub 4 was turned on... but if already on and the netgear turned on it would then work. Even more weird is if I disconnected the cable whilst both were on and plugged them back in, it still wouldn't work so it really did need the full netgear restart. 

Anyway - 4 hours later and I've managed to solve but wonder if anyone may know why!

[Adduxi]

Glad to see you got it working in the end.  Who knows why the tried and tested method failed, but at long as it's working 🙂   I'd hate to be without modem mode.

[mercilesskiller]

Ha indeed - When it stopped working this morning the first thing I did was reset the netgear AND the Hub of course.. but at no point had I tried keeping the hub 4 active and going and ONLY reset the Netgear. But I suppose for others that may come to the forum, sticking to the advice of ensuring the Hub 4 is switched off, initialise the router, and then switch the hub on... sometimes doing it the opposite way will fix it lol

[Roger_Gooner · Accepted solution]

The correct procedure is to power on the hub first and then the router as doing it this way ensure that the hub's modem goes though its complicated initialisation with the CMTS and gets the data it needs from the DHCP server for the WAN IP address and routing table. When you then power on the router all the work has been done by the modem and the router will get its WAN IP address as the modem is acting as a bridge. If you power on the router before the hub there is the risk that the router will fail to get its IP address and/or begin to prematurely assign IP addresses to connected devices, which is why a power recycle of the router will be needed to get it to work.

[mercilesskiller]

Yes that conflicts with what other posters on this forum have seemed to suggest. Lots of posts saying it’s essential to start the router first, let it all initialise and only then turn on the Hub. weird!

[Adduxi]

Yes it’s always been a bone of contention here.  I’ve always powered on the Hub last.  Maybe it’s hardware dependant with different Routers behaviour.  At the end of the day whatever works 🙂

[mercilesskiller]

Darn it. I still have a problem. 

whilst identifying the restart order to fix the issue, it happened again overnight. 

I restarted the router itself and it didn’t fix it. Link light showed as connected to the hub but no internet. So turned both of them off. Turned hub on. Waited. Turned router on and it worked. 

so 2 nights running my hub in modem mode lost its internet connection until a restart. If this is going to be every night that may get frustrating! I could always get plug timers that auto turn off and on at certain times 5 mins apart but that shouldn’t happen ha!