We need to know what path your replication connection is operating in. Start a replication connection and make sure it is alive by running fw ctl multik gconn. If you can't see the connection here it is not alive.
Next run the following while the connection is alive:
fw tab -t connections -z
fwaccel conns
netstat -ni
If you see the replication connection in the output of the first command, the traffic is slowpath and a reason will be provided. fast_accel will not work for this traffic.
If you can't find the connection in the output of the first command it will be shown by the second one which means medium or fastpath.
Please post the output of wherever you find the connection, along with the third command. If fwaccel stat is complaining about stopping on rule #1 it is referring to accept templating which has nothing do with which path the connection ends up in. With just the firewall blade enabled it should be fastpath but Core Activations & Inspection Settings can interfere with this.
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March 27th with sessions for both the EMEA and Americas time zones