Kinda as title says, ever since changing the old router to this even shittier one (not my choice to make) and now e621 loads slowly and I do thought something wrong with the e621 servers but no e926(SFW version of e621) loads instantly no slowdown just like it does for e621 on the old router. Although the router choice was not mine I'm still technical enough to do setups/port forwarding, all I can say is that this router is just straight up overhyped bull crap. there are same problem connecting into Destiny 2 game servers but no problem to bungie net but not part of the problem but maybe link to it.
Edit: it's the same of all devices connected to the same router, only on mobile data the issue is just gone, so it's all on this shitty router.