Is there someone here that actually owns a DrayTek Vigor 166 ?,
and if so, can you answer this MTU question for me ?
According to the DrayTek Vigor 166 specifications this modem supposedly supports MTU=1508 Jumbo Frames (RFC-4638).
1) The Vigor 166 User Guide states that the maximum MTU that can be set is 1500.
2) The original release of firmware didn't support MTU above 1500, and the firmware update history doesn't indicate that ever changed.
3) The similar Vigor 167, does support MTU=1508 but only in 'router' mode but not 'modem' mode ! (added in firmware update 5.2 - according to the release notes)
Before I commit to buying a Vigor 166, it would be nice to know if your device, with the latest v4.2.5_BT firmware, and operating in 'modem' or 'MPoA bridge' mode, whether the web GUI allows you to set the maximum MTU to at least 1508 ?
Fixed! Go to the fix.
Just in case anyone else is interested in the answer to my question,
Yes, the Vigor 166 modem, with v4.2.5_BT firmware, in "MPoA Bridge" mode, DOES support MTU up to 1520.
I was reluctant to spend in the region of £115 for a new Vigor 166, as a marginal upgrade to my trusty Vigor 130, with the uncertainty of whether or not it could support "Jumbo Frames" on the PPP connection.
Having been on the lookout for months on eBay for a used Vigor 166 for less than £50 (Vigor 130's sell for about £30), I'd pretty much given up hope as they were all selling for about £80 to £110, and I didn't want to pay that much for a modem when FTTP might appear in perhaps two years time, and my collection of various modems would subsequently become redundant.
By chance, last week, someone listed a Vigor modem, but the auction title and description contained errors in the model number, but the photo showed exactly the model I was looking for, consequently there were no other 'watchers', no other bidders, and I won the auction for the starting price of just £20 !
The modem arrived on Friday, and it looks completely unused.
Today, I've updated it's firmware, manually entered the configuration, changed the wiring to the router (from one cable on the Vigor 130, to two cables with the Vigor 166), and I am now writing this reply, while connected via the new modem with the PPP link passing traffic with MTU at the full 1500 that Openreach SoGEA is capable of !.
So far, the DS sync is a little faster than the previous modem before disconnection, and seems to be happy at 4dB SNR.
Now I'll have to watch to see whether DLM reacts to the new modem's different VDSL chipset !.