Dialup modem was giving error 721 ppp connection error your remote computer could not be found. Uninstall dial up modem software and reinstall but again same error. Deleted temporary internet files and also checked after disable firewall.
Performed full malwarebyte scanner found malware Hacktool.wpakill entries. Deleted hactool.wpakill entries but still I could not able to connect internet. This was really make me to frustrated now i have only choice to repair windows 7 with system image.
Restarted the windows, hold F8, repair windows 7 and selected recent system ISO image it takes 15 minutes to re image operating system.
For permanent solution restarted system in safe mode with networking scan again with malware byte to ensure really malware and adware entries removed or not but this time no any such entry found in mbm full scanner. Now i open command prompt given some commands to reset ipconfig, dns and winsock setting to fix internet connection errors. Due to dns winsock corrupted I need to perform few commands using command prompts to fix all errors. Having same problem you can also follow same procedure.
Run a chkdsk command to check windows errors. Restart windows 7 check scan disk gives some error. Now i run chkdsk /f /r command to fix and remove windows errors and run sfc.exe /scannow to repair those errors. Now updated latest network adapter driver.
Run command few more commands to reset tcp/ip configuration, flush dns, and reset winsock to fix all errors. You can check dns, ip address and network adaptor details with ipconfig command. Open command prompt and use following commands to reset tcp/ip, renew ipconfig, winsock reset.
- netsh int ip reset resetlog.txt (for reset TCP/IP)
- ipconfig /release
- ipconfig /renew
- ipconfig /flushdns (this command flushout dns)
- netsh winsock reset catalog (for reset winsock)
After all successful command attempts now i restarted windows 7 in normal mode and connected with dial up wireless connection. No error 721 found and even my internet connection works smooth websites load fast. Hope this help you also.