This topic

Full fibre with homehub2

stevenprigg78 — Sat, 06 Jun 2026 18:36:07 GMT

I’ve had a homehub2 for many years, and with adsl (aside from some infrequent modem resyncs) never had any problems

I’ve got quite an elaborate home automation system, homeassistant, solar and battery, ev charger.

up to having full fibre installed, no issues

Shortly after having the fibre modem installed, and connected, we now suffer frequent hub restarts and loss of connection.

Both a “green light” reboot and and “orange light” loss of connection

I’ve contacted bt, they sent a new homehub2, No change after installing.

I’ve checked with my neighbours and they also report a very unstable connection.

my network and setup hasn’t changed at all over the upgrade to full fibre.

it was rock steady stable up until the fibre change over.

openreach are coming out Monday, although I don’t have a permanent fault, just intermittent drop outs and hub reboots

what on earth is going on?

Re: Full fibre with homehub2

iniltous — Sat, 06 Jun 2026 18:50:50 GMT

You need to be looking at the ONT , if the LOS light comes on (loss if signal ) that’s clearly a problem or if the PON light flashes that also is an issue , the router lights in some respects secondary as if the PON has an issue then the router is simply responding to that (in other words if the Openreach network drops the BT router will also drop ) …if neighbours are also having issues that suggests it’s not specific to you but the splitter back to the headend , if that’s the case the repair probably don’t need you to be home.

Re: Full fibre with homehub2

stevenprigg78 — Sat, 06 Jun 2026 18:56:23 GMT

Can the fibre modem prompt a full hub reboot (green light dropout?)

nothing, and I mean nothing in my network has changed since the fibre upgrade.

its the only variable

Re: Full fibre with homehub2

WSH — Sat, 06 Jun 2026 19:29:46 GMT

As iniltous says, if your neighbours are having similar problems then it suggests it is the network outside your house.

However, if the hub is restarting...

You say you've had a new hub. Did you change the power unit or is it still the old one? It may be a failing PSU.

Re: Full fibre with homehub2

stevenprigg78 — Sat, 06 Jun 2026 19:52:59 GMT

Yes, swapped the power supply as well

can the fibre modem prompt a hub restart?

Re: Full fibre with homehub2

WSH — Sat, 06 Jun 2026 19:57:52 GMT

It could cause a resync, hence the orange light.

I don't believe it could cause a restart, the green light. That suggests a power problem.

Re: Full fibre with homehub2

stevenprigg78 — Sat, 06 Jun 2026 20:15:14 GMT

Yeah power supply swapped as well

no problems at all until fibre swap

Re: Full fibre with homehub2

Michael_D — Sun, 07 Jun 2026 09:16:12 GMT

Hi @stevenprigg78

Hopefully the engineer can get to the route of the cause tomorrow, but if it does continue beyond that, I'd recommend getting back in touch with our tech guides so they can look into this further.

Michael

Re: Full fibre with homehub2

pddco — Sun, 07 Jun 2026 14:02:44 GMT

As others have said, with your neighbour also affected it sounds like a local fibre network issue. Yet the restart of the hub seems odd, but just checking all bases. Are the HUB and ONT plugged into the same double socket or extension lead. If so there’s always a chance that there may be a dodgy extension lead or socket?

Re: Full fibre with homehub2

stevenprigg78 — Sun, 07 Jun 2026 14:49:42 GMT

Dodgy in what way? none are on extension leads

the hub is on exactly the same AC outlet it has been for years and years with no issues

brand new hub and brand new power adaptor

Re: Full fibre with homehub2

WSH — Sun, 07 Jun 2026 14:55:51 GMT

What are the PON and LOS lights on the ONT doing during these hub reboots?

Re: Full fibre with homehub2

stevenprigg78 — Sun, 07 Jun 2026 15:01:59 GMT

No idea it’s in my meter cupboard not near the hub so I’ve not checked.

can the ONT cause the hub to reboot?

a brand new hub?

Re: Full fibre with homehub2

pddco — Sun, 07 Jun 2026 15:08:00 GMT

@stevenprigg78 .. That’s fine then.. I’d no idea of the setup, so was just thinking if you had, with having an ONT to power as well, that you may have used a double socket or extension lead that you hadn’t used before. In which case there was a slight possibility that may have been poor connections in the wiring to the socket or internal to the extension lead that may be causing an intermittent power supply issue. Which could trigger the hub restarting. But as it’s been working fine for years, and presumably the ONT is in a socket that’s proven fine, then no problem. Just thought I’d check.

Re: Full fibre with homehub2

iniltous — Sun, 07 Jun 2026 15:51:13 GMT

You ask can the ONT cause the router to reboot , that’s easy to simulate, while everything is stable and ‘working’ , turn the power off to the ONT and observe the router , does it look sync , feeling more adventurous , unplug the optical cable at the ONT (the green plug ) and again observe the router …obviously reconnect the power and optical cable after you have finished ‘testing’ .

You seem a little dismissive of the ONT potentially being the issue , but it’s not the ONT ‘per se’ but the lights on the ONT illustrate what’s going on with the PON (the passive optical network) one thing for certain if the PON has problems the router status is irrelevant , the router can’t stay connected if the PON is ‘down’

Re: Full fibre with homehub2

chrisjp — Sun, 07 Jun 2026 19:22:21 GMT

"No idea it’s in my meter cupboard not near the hub so I’ve not checked"

So can I suggest that you DO check what the lights on the ONT show when you have an outage or a hub reboot, especially if it's just a matter of opening your meter cupboard door and looking?
That way, the community might be able to offer you better advice.

Re: Full fibre with homehub2

stevenprigg78 — Mon, 08 Jun 2026 04:30:13 GMT

I can yes, however if somebody categorically knows whether the fibre modem can cause / prompt a hub reboot it allows me to debug the situation from tge other end

- yes -> could likely be a fibre issue since the whole setup has been done for years before the fibre upgrade

- no -> it’s def a hub issue, somehow

Re: Full fibre with homehub2

stevenprigg78 — Mon, 08 Jun 2026 12:57:36 GMT

It’s not easy to simulate if the ONT can cause the hub to reboot.

why would you think it’s just pulling the Ethernet or pulling the fibre that can do it.

id expect there probably a whole host of ip related commands that can be sent to reboot the HH2

purely the fact that BT can remotely reboot the hub kinda backs up that line of thinking

in wondering if the fibre is unstable enough that maybe a significant loss of SNR equivalent or bad/lost packets can cause the fibre modem to panic reboot the hub.

i wouldn’t imagine this can be easily checked by just yanking connectors out

Re: Full fibre with homehub2

iniltous — Mon, 08 Jun 2026 15:21:39 GMT

1…It’s very easy to power off the ONT to imitate the ONT and headend losing sync , you obviously then can go and check the router to see what the hub lights are doing to demonstrate that the PON going down affects the router .
2… I never mentioned pulling the Ethernet as that’s not part of the PON , unplugging the fibre serves the same purpose as powering off the ONT , but more accurately mimics ( for example ) a break in the fibre back to the headend, in both examples the point was to demonstrate that the router will be affected by issues with the passive optical network (PON) which your previous comments seemed to doubt .
3…Yes the hub can be rebooted remotely with the appropriate command from the ISP , but why would anyone from BT be doing that , and there isn’t really any conceivable fault that would consistently replicate that command anyway , if that is that what you think is happening, checking the ONT will prove or disprove that , as any fault indications on the ONT , that’s the LOS light coming on of the PON light flashing would not occur if your router were simply being remotely reset either deliberately or by some weird non PON related issue .
4…This is exactly why you were asked to observe the ONT when problems are happening.
5…See No.1.

Re: Full fibre with homehub2

WSH — Mon, 08 Jun 2026 18:30:28 GMT

@stevenprigg78

So, what did the Openreach engineer say?

Re: Full fibre with homehub2

stevenprigg78 — Tue, 09 Jun 2026 18:54:14 GMT

Connected his meter and said “well it’s working isn’t it”

didn’t seem interested in my neighbour’s trouble either.

just wanted to get back in his van to say he’d attended.

the definition of a “tick box exercise “