Just had FTTP installed at home. 900Mb symmetrical. Toob is the provider. ADTRAN PON ONT 621li modem https://www.ispsupplies.com/Adtran-1287844F1 . 2766ac router connected via ethernet via WAN2 in DHCP mode.

With the supplied Sagemcom router , I'm getting the full speed. So it must be talking 1000baseTX to the ONT modem.

Connecting the 2766, it's using 10/100baseT and hence speed tests top out at 90Mb/s. Forcing 1000baseT doesn't work.

I've tried different leads, powering things on/off , etc. But I'm stumped. Also tried a 2830 and it too fixes at 10/100. I also tried connecting a MacBook with 1G ethernet to the ADTRAN , and it was 10/100.

What secret sauce is the Sagemcom router providing , which gets the 1G ethernet connection to the ONT?

Looking at the user guide, i wonder if the order you have things on is an issue. So, start with the ONT powered down and connect your draytek to the ont (Draytek powered on). And then start the ONT.
https://www.manualslib.com/manual/2524625/Adtran-621i-Xgs-Pon-Ont.html?page=3#manual

Or have you tried the adtran community forum ?

https://supportcommunity.adtran.com/t5/Discussion/ct-p/discussion

I think there's more to it than the order of switching on, which shouldn't matter anyway.
When my DrayTek router is connected directly from WAN 2 to the ONT I see up to 30% packet loss of pings. When these two connected via a simple gigabit switch there's no packet loss.

My setup:
- FTTP 150 Mb from Swish Fibre with AdTran 622v XGS-PON ONT connected via the 10 Gbit port (as required by Swish).
- ZyXEL GS105B (intermediate switch that shouldn't be necessary).
- DrayTek 2862 with firmware 3.9.8.1_BT set to auto-negotiate.

Tested with a variety of CAT5e and CAT6 cables from 0.5 m to 15 m - making no difference.
Speed test (Think Broadband) returns 160 Mbit each way, so I assume it has negotiated 1000 Mbit on both sides of the switch.
Connecting either my laptop or the Swish-supplied Plume Pod router directly to the ONT shows no packet loss.

Conclusion: there must be some incompatibility between AdTran and DrayTek.

Hi Srooks,

Have you checked the flow control is active?

See this video, at 32m55s:
https://draytek.co.uk/our-solutions/videos/draytek-webinars/draytek-router-wan-performance-and-hardware-acceleration