Try
lxc config device override t1 eth0 limits.ingress=1Mbit
As that command allows overriding multiple keys at once (one per argument) and therefore requires key=value syntax for each argument.
Try
lxc config device override t1 eth0 limits.ingress=1Mbit
As that command allows overriding multiple keys at once (one per argument) and therefore requires key=value syntax for each argument.