So just try to open a VPN connectionThe VRRP Master device stopped accepting VPN connections
ppp profile interface-list
Unsure how to use that setting properly, however with MTU=1420 and MRRU=1600, no clamp in FW nor PPP, I got about 5% less than with MTU=1460.Can you test L2TP ipsec with Multilink Protocol activated - MRRU=1600 on both sides ? Don't use tcp mss clamping - ppp profile set=no on both sites too !
L2TP+IPSec 280 280 120/120 208 200 80/80
/ppp secret disable [find where comment>="1" and comment<="720"]