Either Kenobi or Anakin can solo.
Multiple statements have suited Vader being drastically weaker than his pre-injury self in accordance with Lucas’s vision:
“Under Palpatine's supervision, surgical droids transformed Vader's mutilated body into an armored cyborg. Although the Dark Lord was entirely dependent on his armor's life support systems, and his formidable powers were drastically reduced by his injuries, he remained strong with the Force for the rest of his life.” -Stars Wars Blueprints - The Ultimate Collection
“Darth Vader was encased in sinister black armor. The man underneath was mortally wounded in a lightsaber duel, and the dark suit includes extensive machinery to keep Vader alive. The sounds of his mechanical lungs accompany his every step. Such injuries greatly diminished his ability to use the Force, but Vader is still very powerful.” -Star Wars Encyclopedia — Darth Vader
“And you rage and scream and reach through the Force to crush the shadow who has destroyed you, but you are so far less now than what you were, you are more than half machine, you are like a painter gone blind, a composer gone deaf, you can remember where the power was but the power you can touch is only a memory, and so with all your world-destroying fury it is only droids around you that implode, and equipment, and the table on which you were strapped shatters, and in the end, you cannot touch the shadow.” -Revenge of the Sith
“Where Darth Sidious had gained everything, Vader had lost everything, including—for the moment, at least—the self-confidence and unbridled skill he had demonstrated as Anakin Skywalker.” -Dark Lord: The Rise of Darth Vader
“It was a great pity, Darth Sidious thought, controlling his anger, but perhaps not irreparable. Even diminished, Darth Vader would still be very strong, and there were no Jedi left to challenge him. Darth Sidious had seen to that himself. So he kept walking until he could bend over the body. And to his surprise, his apprentice was still alive.” -Revenge of the Sith Junior Novelization
“An epic duel made impossible by time. The fully grown Jedi Knight Luke Skywalker crosses lightsabers with Anakin Skywalker before his brutal defeat on Mustafar. Both Skywalkers are at the peak of their powers.” -Star Wars Head-to-Head
This lines up with relative feats in-universe as ANH Vader gets out-duelled by a TPM Maul clone on Kalakar Six, then proceeds to be defeated by Luke with minimal training in ROTJ.
He also struggles with numerous lesser Jedi post Mustafar, despite being so dominant in ROTS (even killing Cin Drallig 1 handed while fighting two other Jedi simultaneously, Drallig being the order’s battlemaster and among its greatest fighters), further reinforcing the idea he has been hobbled. These include Bol Chatak, Jastus Farr, Tsui Choi, Bultar Swan, Sha Koon, and Roan Shryne.