Hello all, good review, great thread, some very interesting posts and points of view.
Like many on the board I am having difficulty with the Vigor 166, more specifically the speed at which the modem syncs to the VDSL2 equipment within the cabinet we are hooked up to.
My connection loses 4-5 Mbps (17 down from 21/22Mbps) using the 166, as opposed to either my Openreach ECI modem (B-Focus model) or my ISP supplied FRITZ!Box 7530 Router / VDSL modem combo which sync at a rate up to 5Mbps higher. Our home is a decent way from the broadband cabinet (850M - 900M), typically we enjoy a "stable" but low speed FTTC connection in the 21 Mbps range for downloads and upload speeds of around 4-5 Mbps.
Historically I have used the ECI and more recently the 7530 and sync at around 21-22 Mbps download with a consistent 4.5Mbps upload and a typical 22ms - 28ms ping to UK servers.
This DL speed is instantly reduced when the 166 is connected to the line, upstream remains extant as does the "typical" ping but with large, intermittent latency spikes that can easily be recreated using DSL reports Speed-test where buffer-bloat is off the charts, this does not occur with the ECI modem when using QOS via a UniFi Dream Machine router.
The same router and QOS settings exhibit huge latency spikes when connected to the 166 leading me to believe that the 166 is most certainly the issue.
It's worth noting that the second VDSL Modem code (not default) on the 166 provides marginally higher sync speeds than the factory default setup. Changing the MTU setting for a lower value makes little difference in my case.
The cabinet is the ECI M41 type (FRITZ!box 7530 reports Infinium based hardware and the cabinet type when I checked on Google Maps is commensurate with this)
In addition, like many others I am unable monitor stats to even see if the modem is damaging my line profile as many here have reported, so in the interim I have switched back to the Openreach modem until Draytek fixes whatever is causing the issues or I return the product.
It's a shame as the hardware is clearly well made and has potential longevity that far outweighs my ageing ECI and ISP supplied 7530, but without the ability to monitor the line I simply cannot tell if the modem is performing as it should, couple this with a sync speed that’s 20-25% worse than the ancient hardware that I already use and the 166 is a hard purchase to justify :/