ATT and Site 2 Site Issues Started this AM

[JacoboLevy]

Good Afternoon my fellow Meraki gurus.

We have noticed a weird situation with several of our clients. Site to site is down for sites that have ATT as ISP. if we change the connection to Comcast or any other ISP the Tunnel comes online. ATT tunnel is down. is also blocking our monitoring agents to call back to our colo.

We have talked to ATT using each of the affected client's accounts and no Firewall rules or traffic blocks are being applied on the ATT side. we talked to Verizon on our colo and no traffic is being blocked on the receiving end either.

Again if I change ISP on client side (our agents and VPN tunnels start checking in) on ATT no joy

Tested MX firmware version 16.16, 17.7 and 17.8 same results

[RomanMD]

Most of the time you talk to providers and they say the problem is not on their side. 

I see the need of more troubleshooting...

I would do a trace to see how many providers are involved and would check what MTU is allowed end-to-end... the first step. 

I would also do a packet capture on both ends and see if I receive the packets from remote device...