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# Fixing ERR_SSL_PROTOCOL_ERROR for wildcard custom domains on Vercel

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Beachtownyoga (@beachtownyoga) · 2026-01-13

We have been running wildcard on our custom domain successfully for months. The domain was purchased through Vercel. App is hosted on Vercel.

As of the last couple days, there are certain users with Spectrum internet service provider in the USA that are receiving the `ERR_SSL_PROTOCOL_ERROR`. When they disconnect from wifi and use their cellular network the site loads fine.

subdomains currently used  
`beachtownyoga.yogateq.app` <—currently affected by the error on Spectrum ISP  
`btysafetyharbor.yogateq.app` <— NOT currently affected by the error

Only way to reproduce is if using Spectrum based Wifi. There may be other ISP but thats the one we’ve identified.

What do we need to do with the custom domain in order to fix this issue? Why was beachtownyoga subdomain only affected and not btysafetyharbor?


system (@system) · 2026-01-13

The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for [bonus points](https://community.vercel.com/t/introducing-the-vercel-leaderboard/1358).

https://vercel.com/docs/projects/domains/troubleshooting

You can also use [v0](https://v0.dev/) to narrow down the possibilities.