Dial-up error 633 w/build 15063 Pro

[borate]

Dial up worked fine in 1607. With the update to Creators' build it now reports "error 633 - com port in use."

The modem has always been on COM 3. Tried ports 5, 9, 11. Same. COM 1, the only port listed in Device Manager, is shown as "in use." Process Explorer shows no info when queried for "serial."

Searched, read and tested virtually every suggested fix...

Uninstalled and reinstalled dial-up connection
Uninstalled modem (in Safe Mode), booted normally and updated modem driver
Created a "reservedport" registry entry for port 1723
Ran netstat -aon search for port 1723; it's not listed
Disabled the broadband adapter temporarily and turned off the broadband modem temporarily

SFC /scannow shows no errors.
There are no VPN connections on this PC.
This isn't a modem fault; MS FAX works fine.

There was no DUN failure when 1511 O/S was updated to 1607. Yet, some months later, the 633 error appeared. An earlier 1607 image was restored and DUN was again functional.

Applied Creators' update to that earlier 1607 restore and over a 1511 restore. DUN had been functional on them all until this update broke it. Have others had the same experience? Is there a fix?

 

[DelJo63]

Verify ALL com ports shown ACTUALLY have an associated program, delete those that do not

 

[borate]

Verify ALL com ports shown ACTUALLY have an associated program, delete those that do not

COM1 was the only port listed. Deleted it. No change in DUN. The port reappeared upon hardware rescan or reboot.

 

[borate]

UPDATE
A 4/12/17 phone discussion with MS pegs this as a manufacturer's driver issue, not under Microsoft's control. Precisely whose or which driver is unknown.

 

[borate]

This is not a modem issue. See this thread, and voice your concern...
http://tinyurl.com/m4kjxrj