Same problem here. First experienced it some months ago, and this inicially helped:
https://mtgarena-support.wizards.com/hc/en-us/articles/360000834323-Flush-DNS-and-Winsock-Reset logged in different machines
Was playing with no problems for a month until yesterday when the issue come back, but this time even following the steps above cant log in my account. Tryed in different pcs. Create a new account and weirdly it found no problems logging in
Same problem here. First experienced it some months ago, and this inicially helped:
https://mtgarena-support.wizards.com/hc/en-us/articles/360000834323-Flush-DNS-and-Winsock-Reset logged in different machines
Was playing with no problems for a month until yesterday when the issue come back, but this time even following the steps above cant log in my account. Tryed in different pcs. Create a new account and weirdly it found no problems logging in