Sigh. We're not mind readers. If you want our help, you're going to have to post information that will allow one (or more) of us to help you.
- Make and model of your router.
- Specific router firmware level
- Specific ADSL configurations you tried that failed to work.
- The specific ADSL configuration you set that is now working.
- Name of your ISP.
- WiFi LAN configuration you set that the router "fails to remember"
- WiFi LAN configuration you are using now that appears to work.
Please redact any personally identifying information, such as your publicly facing IP address.
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If this is too much work and effort, then please contact your ISP's support staff, and request from them the support you pay for.