Time Machine TP-Link network drive corrupt .sparesbundle

I can't get reliable performance using Time Machine on a networked drive. …

drive that is connected to my TP-Link AX3000 router.

I wouldn’t expect you would get much of any performance out of that setup. That backup drive configuration is not supported by Apple.

You might have some success if the router is hosted by SMB software that supports the Time Machine over SMB specification (as if it were a NAS). Backup disks you can use with Time Machine - Apple Support

I read that Apple just doesn't support networked time machine anymore

It’s still supported, just not with your setup. I backup several devices over the network to several external drives hosts on my Mini.

I couldn’t find anything in the manual indicating what SMB server it uses not any reference to Time Machine.

may be helpful:

Big Sur + SMB based Time Machine | Apple Developer Forums.

https://www.tp-link.com/us/support/faq/1564/ (How to use Time Machine function on TP-Link routers - case 1).

https://community.tp-link.com/us/home/forum/topic/253936 (Time Machine Backup not working on AX50 on Big Sur).

So for BigSur, smb network drive needed to be formatted with HFS+ ("Mac OS Extended (Journaled)"), then Time Machine sparsebundle backup worked.

Some macOS tries & auto-updates backup drive from HFS+ into APFS, & then problems began to appear.

https://forums.macrumors.com/threads/smb-broken-with-monterey.2324371/ .

Samba (SMB) has began to support Time Machine,

since Samba (SMB) version 4.8 released on March 13, 2018.

But around that same time, Microsoft's own protocol bug was found that exposes security data (this is an example of backdoor), bug was exposed by Secura.

And Samba team (and others) fixed it soon, by adopting a fix/solution that was specified by microsoft itself:

"The default of "server schannel = yes" gives the same protection as Microsoft's "FullSecureChannelProtection=1" registry key (which is the CVE-2020-1472 fix)."

So non-microsoft products / devices / software etc, that uses Samba (SMB), those needed to use "server schannel = yes" ( not the vulnerable settings "server schannel = auto" ), in samba config file,

So all should have updated their samba software to atleast v4.8, or to v4.9 for better safety.

( but some ROM / FW (firmware), etc cannot update their older buggy software easily , unless special firmware updating software/channel etc is used by ROM/FW developer/maker with help of device's user , to update software inside ROM/FW , So w/o such update they remain with old buggy software ).

At this point of time (Jan 2023), Samba (SMB) stable verison 4.17 is better than earlier versions.

If (non-microsoft) devices/items have atleast Samba (SMB) v4.14 or above, then it can be considered as safer.

So some OS, etc, have stopped supporting devices that still uses vulnerable/old settings ("server schannel = auto").

( when devices take samba/SMB based connection related to login, then a test can reveal if its using a secure settings or not ).

Reference info for above data, and for more info:

https://en.wikipedia.org/wiki/Samba_(software) ,

https://www.openwall.com/lists/oss-security/2020/09/17/2 ,

https://nvd.nist.gov/vuln/detail/CVE-2020-1472 .

It’s not just SMB. It is a specification that Apple set that it must support in order to be reliable. As emde-ash noted, if it uses Samba 4.8 or later, it should support the specification.