No group claimed responsibility for the attack in the southern province of Helmand though officials blamed the Taliban, who have a heavy presence in the area.
The bomber rammed the truck into a post manned by pro-government militia members, said Omar Zwak, spokesman for the provincial governor. Seven soldiers and four civilians were killed, he said.
In another attack late on Wednesday, a suicide bomber was killed and six civilians were wounded in a blast in the southeastern province of Khost, police said. There was no claim of responsibility.
The talks between the government and the Taliban began in mid-September in Doha, the capital of Qatar, following a February deal between the terrorists and the United States that has cleared the way for U.S. forces to withdraw from their longest war.
But the talks between the Afghans have become bogged down on processes and procedures, diplomatic sources say.
The Taliban political spokesman, Mohammad Naeem, told Reuters negotiators had not met for the last two days. He did not say why.
U.S. Special Envoy Zalmay Khalilzad, the architect of the February agreement who has been trying to encourage the power-sharing talks between the Afghans, said on Wednesday he was heading to Doha to meet the negotiators."The Afghan people and international community are watching closely and expect the negotiations to make progress toward producing a roadmap for Afghanistan’s political future and a permanent and comprehensive ceasefire," he said on Twitter.