Hello all,
since many years we are running a 3.8.5 mesh with 12 slaves.

Since this morning our Melbourne office is down.

I have tried to restart both master and slave without any luck.
All other sites are working fine.

I have unloaded the filters.
I can see that slave and master are talking to each other.
Timesync is working.

On the IKE screen I can see (among many other things):
Retransmit timer expired...
Peer lost our reply retransmit ...

This has happened one time before and then everything started to work again
after a couple of days.
And as always, the ISP says that they "did nothing".

My guess is that when the master is sending a new certificate that package
is to big and it is discarded on the way down to Melbourne.
How big is this packet from the master?
I can ping 1500 byte big packets but not 1550 byte.

How I can verify that this is the problem?
I have PKTSCAN installed on both machines.

Are there any tools to check if I can send big packets?

Or do you have a better idea?

Appreciate your help.