Operation Stack has been lifted again after it was reintroduced in the early hours of this morning.
It had been brought back less than 12 hours after it was finally ended yesterday, after migrants stormed the Channel Tunnel in an attempt to reach the UK.
Phase two of the operation was put in place around 2am after up to 150 people tried to gain access.
The M20 was closed coast-bound between junctions 8 and 9 until 2pm, leading to queues from J5 and delays in both directions on the A249 at Detling.
Traffic also remains heavy on the M2 and A2 due to diverted traffic.
A police spokesman said: "Phase 2 of Operation Stack has now been lifted having been re-implemented earlier this morning due to disruption at the French side of the Channel Tunnel.
"The M20 is fully open.
"There may still be residual delays in the area while the road network returns to normal."
A Calais port spokesman said earlier that although the incident with the migrants was dealt with within a few hours, traffic was interrupted, with long queues of lorries and cars forming.
Around 3,000 migrants are currently camped out around Calais and are trying to cross the Channel into Britain.
Due to problems with Eurotunnel services there may also be delays to non-freight traffic between J11 and J12 coast-bound.
Travellers are advised to check with their operator before making any journeys towards the tunnel.
It comes after days of travel nightmares, when the motorway was shut both sides following strikes by MyFerryLink workers.
Normal ferry services are now operating at the Port of Dover.