Maintenance for the week of October 12:
• PC/Mac: NA and EU megaservers for maintenance – October 12, 6:00AM EDT (10:00 UTC) – 8:00AM EDT (12:00 UTC)
• Xbox One: NA and EU megaservers for maintenance – October 14, 6:00AM EDT (10:00 UTC) – 9:00AM EDT (13:00 UTC)
• PlayStation®4: NA and EU megaservers for maintenance – October 14, 6:00AM EDT (10:00 UTC) – 9:00AM EDT (13:00 UTC)
They still give exp and item rewards, you have just out leveled them so if they require killing mobs to finish them, you will get no exp or loot from the mobs (mobs 5 levels above or below your level gives no exp or loot except crafting parts) you need to kill but still get loot and exp from the quest hand in
[Indomitable Adventurer] achievement requires you to complete 1500 quests. Considering I did every quest in PvE long, long ago on my main and have done multiple times in Cyrodiil, poking away at that number via PvP is all you have left. If I recall correctly my main's at about 1300 quests completed.