"I also checked browsing the webpage and found that sometimes I cannot even open a webpage."
This happens to me often at 3G with Public Mobile. I thought I was the only one. My internet will be working, then suddenly the webpages will not load. I have an iPhone SE. I wonder if this may be an iPhone issue?
I'm in the Ottawa area as well, and there is definitely something going on in the last few days. I just did some speed tests, and speeds seem to be the same in my current location (Kanata) for LTE connection, but slower than before when I force a 3g connection, see below:
Southern Ontario, in the middle of Brant County - 4.32 download on full LTE plan, 0.37 upload.
Note, inside a bad building for signal right now... but this is slow even for my regular day.
I've been having the same problems lately (I just switched to Public from Virgin). I have to sometimes turn off my WIFI and then turn it back on in order for my internet to not be slow and actually work. I don't use the data Public offers because I mostly like WIFI, but maybe it's just a weird overall issue? My WIFI is with Rogers.
I also have an iPhone SE and I noticed that this all started to happen right after I updated iOS.