My NEC DVD RW -3500AG will record using 8X DVD- R but not 16X can you advise

Have you've tried cleaning the laser with a cleaning disc?

Failing this it may be worth removing the cover and cleaning the lens directly with a QTip and some lens cleaning fluid. Only use a drop and then wipe off with a clean dry QTip.

The other option is that you are using an incompatible format of blank DVDs. I've heard of people having problems using DVD-R & DVD-RW and although it is lised as being suitable for all types of recordable DVDs I belive you're best using DVD+R & DVD+RW.

The Manual states

Recordable disc

• We strongly recommend for good recording quality:

SONY DVD+RW 4x, MAXELL DVD+R 4x/8x/16x, SONY DVD+R 4x/8x/16x, TDK DVD+R 4x/8x/16x,

MAXELL DVD-RW 4x, MAXELL DVD-R 8x/16x

• Discs that have been tested and are proven to be compatible with this recorder:

VERBATIM DVD+RW 4x VERBATIM DVD+R 8x
VERBATIM DVD-RW x VERBATIM DVD-R 8x JVC DVD-RW 4x MAXELL DVD-R 16x

There are DVD+R discs and DVD-R discs. It looks as though your burner will only write to the "+R" discs. I believe that is your problem. Try the +R discs which can be purchased individually or in 3 packs just to be sure. Good Luck.

Try checking your settings in the burn menu.Many programs give you the options to burn at slower rates.Good Luck

They probably will not go up because dvd recording is being replaced by dvr. You can use 16x on your recorder. That is fine. It will still record at 8x, but 16x will work fine.

The LG G20 DVD Rewriter is an advanced external burner that supports 'editable' Rewritable DVD+RW disk.
As a generic comment, not all writable/rewritable media are made equal and problem with branded & unbranded disks are not uncommon, so stick to brands that work for you for your specific unit!
The following is the advertised support for your unit, hope it helps:
Reading Rate DVD-R/-RW/-ROM 16x/13x/16x/16xSL/12xDL max. DVD-RAM 2x, 3x-5x, 6x-12x DVD-Video (CSS) 4,8x max. (Single/Dual Layer) DVD+R/+RW 16x/13x max./ 12xDL max. CD-R/RW/ROM 48x/40x/48x max. CD-DA (DAE) 40x max. Burning Speed DVD-R 2x, 4x CLV, 8xZCLV, 16x PCAV, 20X CAV DVD-RW 1x, 2x, 4x, 6x CLV DVD-RAM 2x, 3x ZCLV, 3x - 5x PCAV, 12x PCAV DVD+R 2.4x, 4x, 8x, 12x, 16x PCAV, 20X CAV DVD+R Double Layer 2.4x, 4x, 10x, 12x ZCLV DVD-R Dual Layer 2x, 4x, 6x CLV, 10x, 12x ZCLV DVD+RW 2.4x, 4x, 6x, 8x ZCLV CD-R 4x, 8x CLV, 16x, 24x, 32x, 40x, 48x ZCLV CD-RW 4x, 8x, 10x CLV, 16x CLV, 24x, 32x ZCLV

I not sure as to which type of Discs that you are refering to (ie DVD+R or DVD+RW). This player will only recognize 4x (max) DVD+RW and 8x (max) DVR+R discs. If the DVD+R Disc is 16x, the DVD recorder will not recognize it once you start to record. The player will read the blank Disc and give the impression that it will record on it. I have noticed that when a 16x speed Disc is in the Drive, The recordable hours for the disc seems to double. The normal 6 Hour recording length comes up as 12 Hours when you hit the info button. Since the 8x Speed (max) discs are not available any longer, I found it best to use the DVD+RW 4x Discs and make it compatible. I then copy the compatible DVD+RW disc to a 16X DVD+R disc using my computer DVD burner. The DVD+RW disc can then be erased so that it can be reused.

Technically, E25 is a copy-protection error, but I have some additional background on this issue. On the one hand, it could be a legitimate copy-protection error - you are trying to record from a copy-once or copy-protected source - this is especially true if you are trying to record from a Cable/Satellite Box that has a DVR box - since copying to the DVR is considered the first "copy," the Magnavox will not allow you to make a "second" copy.

On the other hand, Magnavox/Funai players see all programs recorded in V mode (as opposed to VR mode) as "copy-prohibited". It records all +R discs in VR mode automatically, so the solution in this case would be to record on a compatible -R disc (or vice versa).

There are two simple fixes for this issue in either case:
1) If you are using a +R disc, switch to a -R disc. If you are using a -R disc, switch to a +R disc. Simply switching the disc type will "fix" Magnavox recorders (long story).
2) If your TV has a "Video Out" or "Monitor Out" (most TV's don't), you can connect a yellow video cable from the OUT of the TV to the Video IN on the back of the Magnavox. This will permanently resolve your problem by fooling the recorder.

Here is additional info about the type of disc to get:
IDiscs that have been tested and are proven to be compatible with this recorder:
VERBATIM DVD+R 8x, VERBATIM DVD+RW 4x
VERBATIM DVD-R 8x, VERBATIM DVD-RW 2x, MAXELL DVD-R 16x, JVC DVD-RW 4x
IWe strongly recommend for good recording quality:
TDK DVD+R 4x/8x/16x, SONY DVD+R 4x/8x/16x, MAXELL DVD+R 4x/8x/16x, SONY DVD+RW 4x,
MAXELL DVD-R 8x/16x, MAXELL DVD-RW 4x

Good Luck!

-Tha Mp3 Doctor

Dunno. Do you have the latest firmware?

2f8 released August 24, 2008 is the latest version

=> http://www.findmysoft.com/drivers/Nec-ND-2510A-2f8-firmware-driver.html

Make sure the discs you are using are the same as the ones listed as compatible in the manual:

• DVD-RW ver. 1.1 / 1x / 1x to 2x, ver. 1.2 /
2x to 4x / 2x to 6x
• DVD-R ver. 2.0 /1x / 1x to 4x /
1x to 8x / 1x to 16x, ver. 2.1 / 1x to 8x / 1x
to 16x
• DVD+RW 1x to 2.4x / 1x to 4x / 3.3x to 8x
• DVD+R 1x to 2.4x / 1x to 4x / 1x to 8x / 1x
to 16x
• DVD-RAM ver. 2.0 / 2x, ver. 2.1 / 2x / 2x to
3x / 2x to 5x, ver. 2.2 / 2x / 2x to 3x / 2x to 5x
• DVD-R DL ver. 3.0 / 2x to 4x
• DVD+R DL 2.4x / 2.4x to 8x

Any brand can be used.

Try this download page to update your firmware from 25/10/05, so if you bought your writer before this date maybe this will work, otherwise buy 8x discs. http://sony.storagesupport.com/dvdrw/firmware.htm#710 The faster the discs are burned the more chance of errors there are, you should write at slower speeds for better quality.