Why is my Docomo Hikari slow in the evening?

Evening slowdowns (19:00-24:00) on Hikari fibre are almost always caused by PPPoE congestion at NTT's NTE network termination equipment. Switching to IPoE (IPv4 over IPv6) via services like 'v6 Plus' or 'OCN Virtual Connect' bypasses this bottleneck and can dramatically improve evening speeds from 10 Mbps to 500+ Mbps.

Should I choose Docomo Hikari or home 5G?

Hikari is better for consistent low-latency needs like competitive gaming, file uploads, and video calls. Home 5G is better for convenience — no construction needed, plug it in and go. For most households, Hikari provides more stable performance, but home 5G in a strong 5G area can exceed 500 Mbps.

DoCoMo Speed Test — Japan's 5G and Hikari Fibre

NTT DoCoMo is Japan's largest mobile carrier and a subsidiary of NTT Group, the company that built Japan's entire telecommunications infrastructure. DoCoMo offers internet through two fundamentally different services: Docomo Hikari (光) — fixed fibre broadband running on NTT East/West's GPON network — and home 5G — a plug-in wireless gateway that delivers broadband over DoCoMo's cellular 5G/4G network.

Understanding the difference between these two services is crucial because they produce very different speed test results, have different strengths, and are affected by completely different problems.

Docomo Hikari vs Home 5G — Quick Comparison

Feature	Docomo Hikari (Fibre)	Home 5G (HR02)
Max Download	1 Gbps / 10 Gbps	4.2 Gbps (theoretical)
Max Upload	1 Gbps	218 Mbps
Ping	5-15 ms	25-60 ms
Stability	Very stable	Varies by signal/time
Installation	Construction needed (工事)	Plug in immediately
Data Cap	None	Soft cap (heavy use throttle)
Best For	Gaming, uploads, stability	Renters, temporary housing

The PPPoE vs IPoE Problem (Hikari)

Japan's fibre internet has a unique problem that most countries do not face: PPPoE congestion. NTT's older connection method (PPPoE) routes traffic through congested Network Termination Equipment (NTE) points. During evening peak hours (19:00-24:00), users on PPPoE can see speeds drop from 500 Mbps to as low as 5-10 Mbps.

The solution is switching to IPoE with IPv4 over IPv6 — services marketed as "v6 Plus" (JPNE), "OCN Virtual Connect", or "transix". This bypasses the PPPoE bottleneck entirely:

Check if your provider supports IPoE (most do in 2026)
Ensure your router supports MAP-E or DS-Lite protocols
Contact DoCoMo to enable the IPoE option on your Hikari contract

After switching, evening speeds typically jump from single-digit Mbps to 300-800 Mbps on the same 1 Gbps plan.

Home 5G Router (HR01/HR02) Setup

Setting	Details
Admin URL	web.setting or 192.168.128.1
Default Password	Bottom sticker (初回ログインパスワード)
Location Lock	Must register address via My DoCoMo

Signal Light Guide (HR02)

Blue: 5G connected (strong signal). Best performance.
Green: 4G LTE connected (strong). Good but slower than 5G.
Yellow: Weak signal. Move router to a window facing a DoCoMo cell tower.
Red: No service or SIM error. Re-insert SIM card. If persistent, call 151.

Japanese ISP Alternatives

SoftBank Hikari — Also uses NTT fibre. Good for SoftBank/Y!mobile phone bundling discounts.
au Hikari (KDDI) — Uses KDDI's own fibre network (not NTT). Often faster evenings because less shared congestion.
NURO Hikari (Sony) — Uses NTT dark fibre with GPON that is provisioned differently. Often the fastest option in covered areas.
Rakuten Turbo — 5G home wireless, similar to DoCoMo home 5G but on Rakuten's smaller network.

DoCoMo support: Call 151 (from DoCoMo mobile) or 0120-800-000 (free from any phone). The My DoCoMo app provides usage tracking, address registration for home 5G, and contract management.