Could you alaborate more on your config. Read this topic please: Getting the most out of this forum
My first thought is ... "uses VLAN1 tagged with tag 1". Look there: The twelve Rules of Mikrotik Club and there GP & CSA for Mikrotik devices
It would help if you can show your config.
The error you show is strictly JavaScript one and it's hard to say what and where software wants to connect when the error occures.