I am having intermittent access to the internet via VPN, via Accountable2You, on an iPhone SE-2. iOS 15.2, T-Mobile48. Accountable2You indicates " Some carriers prohibit (or slow) VPN traffic from mobile devices. In most cases, this restriction can be removed by contacting your mobile service provider. " Could this be the cause?
Sometimes it works great! Sometimes it is very slow pulling up a website. Sometimes it never pulls up the site at all the first time and requires multiple retries.
I have contacted T-Mobile. Waiting on a reply.