Three's 4G service is highly contended in peak hours in some area's, and in the UK 5G depends on 4G for the uplink. If you are in one of these area's the 5G will not get better until the 4G is fixed. Some people get good speeds by using a VPN which bypasses the traffic shaping or just bad setup of Three on contended masts.
700MHz indoor/landmass coverage should be live now where 5G is and that should make a big difference to upload of basic clicks whilst navigating the internet.
4G Band 20 800MHz is again more than ample for clicking links uploading basic ‘move to here‘ commands, uploading esp large files will be down really to 5G SA splicing .
There really shouldn’t be a saturation issue on 5G upload spectrum like 4G, they maybe one generation but even (4.5G NSA) 5G is light years ahead in how it does not saturate like 4G, 5G SA again is light years ahead of NSA in generational terms of what the tech can do with speed.
4G here in my area of the city is saturated on all networks, & thats before the impact of Covid.
Three isn’t the worst EE is, Three performs 3 times better as a minimum, o2 & Voda get twice the speed of Three, Lycamobile generally hits its o2 100Meg 4G cap but saturation still happens off peak of 9-5pm office hours.
5G sails on both V/o2 but I have noticed I have to reboot 5G much more than 4G, it’s just one of the things of NSA being a cross breed of 4/5G, it’s a stop gap the UN ITU agreed on to fulfill networks cries that 4G was breaking & it couldn’t wait for 5G SA specs to be agreed as everyone is demanding more and more 4G data off a wired connection.
For me VPN only slows 5G as a work around and uploads can be even more horrific, much easier just to reboot 5G that doesn’t have the same issue as wired copper line reboots causing problems.