I remember in DS1 matchmaking was linked to the maximum upgraded weapon you have in your inventory, but the streamers I follow only mention Soul Levels while playing online. Does Soul Level (SL) play a part in online matchmaking? How about weapon upgrades?
Please share sources in your answer, so that people can read up on it.
I capped my level at SL 35 (as a personal PvE challenge), but recently upgraded my main weapon to +10. I now notice that the online play on this character is almost non-existing, both invasions and summons.