Last year, there was a post about an upload issue on Croatian 4g network carriers Tele 2/ Telemach and T-mobile. There was one answer where a tp link official @Sunshine posted a firmware update that stated:

We have a firmware related to the MTU size and please have a try and post here with further updated news.

Seems that firmware update did fix this issue but not all bugs with this device. Link for update file containing needed fixes was posted in one of the answers  and sent in private message. I checked official firmware versions but last one available was older than firmware sent with 4g upload issue fix.

Since this is a old and locked topic, may i ask for a locaton of newer versions of firmware or patches containing update file with fix and maybe instructions how to apply it.

This model is stil available for purchase in our country and problem still persists unfortunately.

Thank you in advance.

P.s. locked topic on link:

https://community.tp-link.com/en/home/forum/topic/234510