Afternoon all
Had a play with with the 2.5g ports on the draytek 3910 since I've got two pc's one with a 10 gig port the mac mini, and my pc with a built realtek 2.5gb card.
First the auto detect is a rather flakey. The mac mini won't get a dhcp address if you set it to auto detect the settings. The work around is to set it to manual and the speed to auto detect and it gets an ip address.
2nd on the pc with the realtek enabling jumbo frames drops the network speed down to 1gig connection disable jumbo frames and you get the full 2.5gig. However actually doing a data transfer i.e a backup is actually half the speed the of the intel l211 card with jumbo frames.
Tried different drivers still the same.
Next I got a asus 10gb card slapped that in the pc this will negoatate the speed and get an ip address however with jumbo frames selected you're speed is down to a nearly a gig connection. Iperf3 gives a figure just over a gig so I'll keep using that and see what the backup speed is later.
All cables are cat 6 latest drivers installed.

Tried with a backup and the performance was very poor less than half that I would get into a gigabyte port so at the moment I wouldn't advise people not to use those ports until a firmware fix comes along unless it's a hardware limitation then they are probably only useable as wan ports.

Maybe it's a compatibility issue between some specific 2.5Gb adapters and the 2.5Gb ports on the Vigor 3910. Please report these issues when you see them so that they can be resolved.

I don't think the 10gb ports were tested with a Mac Mini so if you're seeing issues with that, please report that too. I notice that's RJ-45 10GbE so it's worth mentioning which transceiver you're using to convert the SFP To RJ-45 too.

Okay since I've got several devices that have a 10 gig card I bought a ten gig switch. Everything work as it should when using that so definatley a bug with the draytek 3910.
Draytek acknowledged the ticket but haven't been back since. I will wait until and if they don't raise another ticket.
The 3910 is still in beta stage really like the 2960 was when that was released. However it is usable where the 2960 wasn't until quiet a few firmware releases.
The biggest bug is ever so often you lose internet connectivity although browsing round the local network is fine. The draytek thinks it's connected and some devices maintain their connectivity. Sometimes a just releasing and renewing fixes it or other times you have to reboot the router to fix it.
The other bug is failure when it doesn't restore the connection back to the correct wan even if a new session is opened. Release and renew fixes that but it should switch over and sometimes it does.

Nothing from draytek since the acknowledged the ticket. Need to raise another one with them as well.

oops I've noticed they have replied got lost in the 100's of other emails.

Well done the tests to show draytek that 2.5gb ports aren't working the way they should. Lets see what they say.