MX Security Appliance with BT Fibre

[ScubaSteve007]

I managed to get an MX75 connected to BT Fibre (FTTC / FTTX) directly yesterday with PPPoE.    My observations are:

Internet worked, did see a few seconds delay accessing some connections using iPhone Apps, Banking, WhatsAPP etc, seemded to hang for a second or too and then worked.

SKY Stream however was problematic.     Slow to change menu items and streaming of TV channels would freeze for a few seconds every 3 to 5 minutes.        Observed this behaviour for an hour then switched back to the DrayTek Router connected to BT Fibre which then goes to MX64 and no problems at all.   I suspect if I swap the MX64 for the MX75 all will be well too.

It would seem that using the MX to connect directly to PPPoE with BT Fibre causes this behaviour.   

Has anyone seen the same issue or even corrected it.    Trying to get rid of 2 units and replace with one.    If I can't get the MX75 stable then might as well loose it and just go with a new DrayTek Router and use Firewall and VPN on that.

Steve

[ww]

Mx with pppoe uses  max 1492 bytes.

Can you check what the draytek router uses for mtu? Can you do "ping 8.8.8.8 - l 1472 -f"  when connected to the draytek?

[ScubaSteve007]

DrayTek is/was set to 1492   which connected to the MX64.  No problems on this set up

BT Business Hub is now connected instead and to the MX64. No problems on this setup

MX75 with no router and direct WAN to Fibre Port and the problems occur.   So if the MX75 is using 1492 then there is no reason I would think that this is the problem????

[cmr]

Do you have IPv6 set up on the MX75, if so disable it.  I had BT fibre and their IPv6 implementation caused me untold pain, ended up turning IPv6 off and it was fine.

[ScubaSteve007]

Good idea.....I'm using IPv4 however IPv6 could still be enabled.     I will test in the next few days

[PhilipDAth]

Some carriers (I don't know if BT is one of them) support "baby giant" packets - a packet with up to 1508 bytes.

You could try raising a support ticket with Meraki and ask if they can set the MTU to 1508 and see what happens (PPPoE has 8 bytes of overhead, so this leaves you with a standard 1500 byte frame after PPPoE has been removed).  One of two things usually happens - it completely breaks or it works.