Your service works on your ISP. That's not enough. Your customers use many ISPs. Test on all of them.
In my first year as a British IPTV reseller, I tested only on my own Virgin Media connection. It worked fine. Then customers on BT started complaining. I had no idea.
Here's the thing. Your IPTV reseller panel works the same regardless of ISP. But ISPs treat traffic differently. What works on Virgin may buffer on BT. What works on BT may fail on TalkTalk.
Most IPTV reseller operators test only on their own connection. They assume all ISPs are equal. They're not.
What actually works is testing your service on every major ISP before offering it to customers. Virgin Media. BT. Sky. TalkTalk. Plusnet. EE. Each has different routing, different throttling policies, different peak hours.
A smart British IPTV reseller I knows has friends on different ISPs. He pays them small amounts to test his service. He knows which ISPs work well and which need a VPN.
Here's a real-world example. Reseller A tests only on Virgin. Launches service. BT customers complain. Reseller B tests on 5 ISPs. Knows that BT needs a VPN. Tells BT customers upfront. Fewer complaints. Same IPTV panel . Different testing.
The pattern is that ISP testing is market research. It tells you where your service works well. It tells you where you need workarounds.
How to test. Get a pay-as-you-go SIM from each major mobile network. Use hotspot to test. Or ask friends. Or use testing services. Test during peak hours. Test popular channels. Document results.
I have a spreadsheet of ISP performance. Virgin: excellent. BT: good with VPN. Sky: acceptable. TalkTalk: requires VPN. I share this with customers. They appreciate the honesty.
If you're currently testing only on your own ISP, expand your tests. Your customers will thank you. Your support tickets will drop.
The ISP that breaks your service is not your enemy. It's data. Use it.