In this paper, we propose a novel approach in hardware and software architecture design for implementation of remote laboratories for automatic control. In our contribution, we show the solution with flexible connectivity at back-end, providing features of multipurpose usage with different types of experimental devices, and fully configurable client side application at front-end. The physical setup and communication principles of hardware architecture are based on two types of devices: the programmable logic controllers and industrial network routers. The user interface of client application is designed as a Web page, powered by optimized JavaScript, using the sophisticated on-the-fly content generation. To prove the suitability of the architecture, we compare it with other existing approaches of remote laboratory design. We evaluate their benefits and weaknesses, especially in terms of expense, implementation difficulty, and versatility of usage. In this paper, we also show a detailed example of remote laboratory implementation based on new architecture for thermo-optical educational system and provide three other examples of developed remote laboratories. Evaluation of remote laboratory usage and its benefits is provided to demonstrate the learning value of proposed architecture in education process.